Planographic printing plate precursor, substrate for the same and surface hydrophilic material

ABSTRACT

A planographic printing plate precursor comprises a substrate having disposed thereon a hydrophilic layer which includes hydrophilic graft chains and a crosslinked structure formed through hydrolytic polycondensation of an alkoxide of an element selected from Si, Ti, Zr and Al. An aluminum substrate for a planographic printing plate includes a hydrophilic surface which is formed by a hydrophilic polymer including a functional group that chemically bonds to the aluminum substrate directly or is chemically bindable to the aluminum substrate via structural component having a crosslinking structure. A surface-hydrophilic member comprises a substrate having disposed thereon a hydrophilic layer, wherein the hydrophilic layer includes hydrophilic graft chains and a crosslinked structure formed through hydrolytic polycondensation of an alkoxide of an element selected from Si, Ti, Zr and Al.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of application Ser. No.11/298,682, filed on Dec. 12, 2005 which is a divisional of applicationSer. No. 10/166,201, filed on Jun. 11, 2002 now abandoned, which claimsthe benefit of Japanese application nos. 2001-175952, 2001-175953,2001-175954 and 2001-175955, all filed on Jun. 11, 2001, and JapaneseApplication No. 2001-269833, filed on Sep. 6, 2001, the contents of allof which are incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a novel planographic printing plateprecursor. In particular, the invention relates to a novel planographicprinting plate precursor that is scanning-exposed to laser light on thebasis of digital signals, has excellent sensitivity and resistance tostains, and with which easy in-printer development is made possible. Thepresent invention also relates to a novel surface hydrophilic materialand a substrate used for a planographic printing plate precursor whichare excellent in hydrophilicity and durability.

2. Description of the Related Art

Planographic printing utilizes plate material including an ink-receivinglipophilic region and an ink-repellent region (hydrophilic region) thatreceives dampening water without receiving ink, and photosensitiveplanographic printing plate precursors (PS plates) are currently beingwidely used.

PS plates typically comprise a support, such as an aluminum plate,having disposed thereon a photosensitive layer. The PS plate is exposedimagewise and developed, whereby the photosensitive layer in a non-imagearea is removed, and printing is conducted utilizing hydrophilicity ofthe support surface and hydrophobicity of the photosensitive layer in animage area. It is necessary for the support surface to be highlyhydrophilic in order to prevent the non-image area from being stained.

Conventionally, anodized aluminum plates or anodized aluminum plateswhich is subjected to silicate treatment in order to raisehydrophilicity have been used for the hydrophilic support or ahydrophilic layer. Much research relating to hydrophilized substrate andhydrophilic layers using such aluminum supports is being conducted. Forexample, Japanese Patent Application Laid-open (JP-A) No. 7-1853discloses a support processed with an undercoating agent ofpolyvinylphosphonic acid, and JP-A No. 59-101651 discloses using apolymer including a sulfonic acid group as an undercoat layer underlyinga photosensitive layer. In addition, there have also been proposals touse polyvinylbenzoic acid and the like as an undercoat agent.

There have been many proposals with respect to hydrophilic layers whenflexible supports comprising PET (polyethylene terephthalate) orcellulose triacetate rather than using a metal support such as aluminumare used. For example, JP-A No. 8-292558 discloses a swellinghydrophilic layer comprising a hydrophilic polymer and a hydrophobicpolymer, EP No. 0709228 discloses a PET support including a microporous,hydrophilic crosslinked silicate surface, and JP-A Nos. 8-272087 and8-507727 disclose a hydrophilic layer that contains a hydrophilicpolymer and is cured with hydrolyzed tetraalkyl orthosilicate.

These hydrophilic layers are more hydrophilic than conventional ones,and provide planographic printing plates with which stainless prints canbe obtained when printing is initiated. However, there are problems inthat the layers peel during the course of repeated printing and theirhydrophilicity drops over time. There is thus a demand for planographicprinting plate precursors with which many stainless prints can beobtained without the hydrophilic layer peeling from the support andwithout surface hydrophilicity dropping, even in severe printingconditions. There is also a demand for improved hydrophilicity from apractical perspective.

Numerous studies have been conducted in regard to printing plates forcomputer-to-plate systems, the development of which has been remarkablein recent years. Development-less planographic printing plate precursorsthat can be set in a printer to print without being developed afterexposure are being researched with the aim of boosting processrationalization and solving the problem of waste treatment, and variousmethods have been proposed.

Namely, there has been the desire to simplify or eliminate altogetherhaving to dissolve and remove the non-image area with an alkalideveloping solution (additional wet processing), which is customary inconventional processes for producing planographic printing plates.Particularly in recent years, because disposal of waste solutiongenerated by wet processing is becoming a great concern in the entireindustry in view of the global environment, the demand for improvementcontinues to grow ever stronger.

In response to this demand, there has been proposed a method using aprinting plate precursor disposed with a thermosensitive recordinglayer, in which the non-image area is removable during the course ofordinary printing. After being exposed, the printing plate precursor isdeveloped in a printer to obtain a final printing plate. Specifically,the exposed printing plate precursor is mounted on a cylinder in theprinter without having been developed by a developer, and the non-imagearea of the planographic printing plate precursor is removed with inkand/or dampening water supplied thereto while the cylinder is rotated.This is referred to as in-printer development.

Planographic printing plate precursors suited to in-printer developmentmust have a photosensitive layer that is soluble in dampening water orin an ink solvent, and they must be suitable for development in aprinter set in a luminous room.

WO 94/23954 discloses a printing plate comprising a support havingdisposed thereon a crosslinked hydrophilic layer containingmicrocapsules of a thermo-fuseable substance. The microcapsules arebroken by the action of heat generated in the region exposed to a laserlight, and a lipophilic substance dissolves out of the brokenmicrocapsules to thereby hydrophobicate the surface of the hydrophiliclayer. Although the printing plate precursor does not requiredevelopment, there is a problem in that the hydrophilicity anddurability of the hydrophilic layer disposed on the support areunsatisfactory, and stains gradually appear in the non-image area in thecourse of printing.

One promising example relating to a thermosensitive recording layerhaving excellent in-printer developability is a thermosensitiveplanographic printing plate precursor that includes, as athermosensitive image forming layer, a hydrophilic layer that containshydrophobic thermoplastic polymer particles dispersed in a hydrophilicbinder polymer. This printing plate precursor utilizes the principlethat, when heat is applied to the thermosensitive layer, the hydrophobicthermoplastic polymer particles fuse, and the surface of the hydrophilicthermosensitive layer changes into a lipophilic image area.

However, while such planographic printing plate precursors exhibit goodin-printer developability, there is a problem in that thermal energy isnot sufficiently used in the image forming reaction due to the generatedheat being diffused into the aluminum support in the precursor, andsensitivity is therefore low. Another problem is that, when fusion ofthe particles is insufficient, the image area of the thermosensitivelayer becomes weak and printing durability becomes insufficient.

As a countermeasure, JP-A No. 2001-213062 proposes disposing aninsulation layer comprising a water-insoluble organic polymer betweenthe aluminum support and the thermosensitive layer. With this insulationlayer, it has become possible to improve sensitivity without loweringprinting durability. However, with regard to hydrophilicity of thesupport surface, there is still room for improvement in view ofmaintaining high hydrophilicity wherein stains do not appear in thenon-image area over a long period of time.

On the other hand, resin films have been used for various purposes, andsurfaces thereof have hydrophobic property in general. Almost inorganicmaterials such as glass and metal also have hydrophobic property. Ifsurfaces of the films and materials have hydrophilicity, water dropletscan adhere thereto, spread uniformly and forms water-film thereon.Therefore, cloud or mist can be prevented. Further, due to thehydrophilicity, unpreferable hydrophobic contaminants such as sealant,grease and combustion product such as carbon black, which are comprisedin municipal soot, automotive exhaust gas and the like, are hard toadhere to the film and the like. Even if the hydrophobic contaminantsadhere to the film and the like, it is easy to remove the hydrophobiccontaminants by washing it or rain. As a method for providinghydrophilic property to a surface of the materials, etching method andplasma method have been proposed, and these methods can provideexcellent hydrophilicity thereto. However, the effects thereof can notbe maintained. Further, a surface hydrophilic coating film comprisinghydrophilic polymer is also proposed (Dairy Chemical Industry NewsPaper, Jan. 30, 1995). However, when the coating film is provided on asubstrate, an affinity of the coating film and the substrate isinsufficient. Furthermore, a film wherein titanium oxide is used isknown. For example, a layer comprising a photocatalyst is disclosed inPCT/JP96/00733. The layer is provided on a substrate, and the surfacethereof has excellent hydrophilicity in accordance with an opticalexcitation due to photocatalyst. However, a hydrophilic film comprisingthe titanium oxide has insufficient film strength.

SUMMARY OF THE INVENTION

The present invention was devised to solve the conventional problemsnoted above. It is an object of the invention to provide a positive ornegative planographic printing plate precursor that exhibits improvedresistance to stains during printing and with which numerous printshaving no stains can be obtained even in severe printing conditions, bydisposing a hydrophilic layer that has high hydrophilicity and maintainsthat hydrophilicity well.

It is another object of the invention to provide a planographic printingplate precursor that can be scan-exposed on the basis of digital signalsand processed into a printing plate by simple aqueous development afterimage formation or mounted directly into a printer and printed withoutconducting special development.

The present inventors have studied to achieve the objects describedabove and have found that the problems can be solved by forming ahydrophilic layer of a crosslinked organic/inorganic composite whichcomprises a specific hydrophilic polymer, and have completed a firstaspect of the present invention.

The first aspect of the present invention is a planographic printingplate precursor comprising a substrate having disposed thereon ahydrophilic layer which includes hydrophilic graft chains and acrosslinked structure formed through hydrolytic polycondensation of analkoxide of an element selected from Si, Ti, Zr and Al.

The inventors have also found that excellent effects were obtained byfurther providing at least one of specific image-forming layer on thehydrophilic layer of the first aspect of the present invention. Examplesof the specific image-forming layer include an image layer containing apolymer compound including a functional group that changes from one ofhydrophilic to hydrophobic and hydrophobic to hydrophilic in thepresence of an acid, by application of heat, or by irradiation withradiation, and an image-forming layer including a hydrophobic precursorand a hydrophilic resin. The inventors have also found that excellenteffects were obtained by further providing a compound that forms ahydrophobic surface region by application of heat or irradiation withradiation to the hydrophilic layer of the first aspect of the presentinvention. These specific image forming layer and compound may bepreferably applied to and usable for following second and third aspectsof the present invention.

In the planographic printing plate precursor of the present invention,the hydrophilic layer comprises hydrophilic graft chains and acrosslinked structure which is formed through hydrolyticpolycondensation of an alkoxide. The alkoxide is an alkoxide of anelement selected from the group consisting of Si, Ti, Zr and Al. Thehydrophilic layer preferably contains a hydrophilic polymer compoundrepresented by the following general formula (I):

wherein each of R¹, R², R³ and R⁴ independently rep-resents a hydrogenatom or a hydrocarbon group having 1 to 8 carbon atoms; m is an integerof 0 to 2; n is an integer of 1 to 8; L represents a single bond or anorganic linking group; Y represents —NHCOR⁵, —CONH₂, —CON(R⁵)₂, —COR⁵,—OH, —CO₂M or —SO₃M; R⁵ represents an alkyl group having 1 to 8 carbonatoms; and M represents one of a hydrogen atom, an alkali metal, analkaline earth metal and an onium.

In the present invention, the hydrophilic layer is preferably formed bypreparing a coating liquid composition including the hydrophilic polymercompound represented by general formula (I) and a crosslinking componentrepresented by the following general formula (II), applying the coatingliquid composition onto a surface of the substrate, the substratecomprising aluminum, and drying the coating liquid composition.

general formula (II)(R⁶)_(m)—X—(OR⁷)_(4−m)

In formula (II), each of R⁶ and R⁷ independently represents an alkylgroup or an aryl group; X represents Si, Al, Ti or Zr; and m is aninteger of 0 to 2.

Though it is not clear, the mechanism of the present invention may be asfollows: The hydrophilic layer formed on the substrate has hydrophilicgraft chains and has a crosslinked structure formed through hydrolyticpolycondensation of an alkoxide comprising any of Si, Ti, Zr and Al.Hydrophilic functional groups in the graft chains exist in a state offree and unevenly on the surface of the layer. Further the layercomprises an organic/inorganic composite film having densificatedcrosslinking structure, formed through hydrolytic polycondensation of analkoxide. Therefore, the hydrophilicity and the strength of the film areboth excellent.

Concretely, when a hydrophilic coating liquid composition that containsa hydrophilic polymer compound represented by the formula (I) isprepared and applied onto a substrate to form a hydrophilic layerthereon, the silane coupling groups in the hydrophilic polymer compoundinteract with each other to form a crosslinked structure of Si(OR)₄, andthe layer can provide high printing durability owing to the strongcrosslinking structure formed therein. Further, since the position ofthe hydrophilic group comprised in the hydrophilic polymer compound is atermination (end) of a straight chain-like stem portion of the compound,mobility of the group is high. Therefore, in printing with the printingplate, dampening water can be rapidly supplied and drained from thelayer. Further, the non-image area of the layer is effectively preventedfrom being stained since the layer has high hydrophilicity owing to thegroup. Accordingly, it is supposed that the printing plate can produceimages of high quality due to above characteristics. In addition, whenthe crosslinking component of formula (II) is comprised in thehydrophilic coating liquid composition, a crosslinked structure havinghigher density can be formed in the hydrophilic layer owing to theinteraction between the silane coupling groups and the crosslinkingcomponent. Therefore, it can be expected that the film strength of thelayer is further improved to have higher printing durability.

Moreover, in the present invention, an image forming layer (recordinglayer) that contains a polymer compound having a functional group thatchanges its property from one of hydrophilic to hydrophobic andhydrophobic to hydrophilic, by application of heat, in the presence ofan acid, or by irradiation with radiation (the functional group will behereinafter referred to as a polarity-changing group) can be provided onthe hydrophilic layer. Therefore, an image can be formed on theplanographic printing plate precursor of this embodiment throughshort-time scanning exposure to laser light. In addition, the image areaand the non-image area are formed in the hydrophilic layer by changingthe polarity of the layer surface through the scanning exposure and thelike. Therefore, the printing plate precursor of this embodiment enablesin-printer development merely requiring simple treatment with water ornot requiring any specific development at all, and the precursor can bedirectly set in a printer and processed into a printing plate.

The polarity-changing group in the polymer compound that can becomprised in the image forming layer includes two groups, a functionalgroup that changes from hydrophobic to hydrophilic, and a functionalgroup that changes from hydrophilic to hydrophobic. Depending on thetype of the polarity-changing group in the polymer compound to be usedtherein, the planographic printing plate precursor can be formed intoeither positive or negative printing plate, when the plate precursor hasthe same layer constitution. This is another advantage of the precursor.In the planographic printing plate precursor of the present invention, ahydrophilic layer having a crosslinked structure of an organic/inorganiccomposite with a specific hydrophilic polymer, and an image forminglayer (photosensitive or thermosensitive recording layer) may be formedin that order on a substrate.

In the present invention, a compound capable of forming a hydrophobicsurface region may be added to the hydrophilic layer in order that thelayer serves as an image forming layer. In the matrix comprising thehydrophilic polymer compound in this embodiment, the compound which canform a hydrophobic surface region is comprised. The compound such asthermo-fuseable hydrophobic particles fuses to each other in the regionwherein heat is applied or radiation is irradiated to form a hydrophobicregion, and an image can be formed on the hydrophilic layer throughshort-time scanning exposure to laser light light. The non-image regionof the hydrophilic layer keeps high hydrophilicity since the filmstrength of the layer is high. Therefore, the printing plate precursorof this embodiment realizes in-printer development merely requiringsimple treatment with water or not requiring any specific development atall, and it can be directly set in a printer and processed into aprinting plate therein. The planographic printing plate precursor of thepresent invention can have, on a substrate, a hydrophilic layer having acrosslinked structure of an organic/inorganic composite with a specifichydrophilic polymer, and the hydrophilic layer contains a compoundcapable of forming a hydrophobic surface region such as thermo-fuseablehydrophobic particles. In the precursor of this embodiment, therefore,the hydrophilic layer serves as an image forming layer.

In the present invention, an image forming layer (recording layer) maybe provided on the hydrophilic layer, and the image forming layercontains a hydrophobic precursor which is capable of forming ahydrophobic region, and a hydrophilic resin serving as a film-formingmaterial. Optionally, a light to heat (photo-thermal) converting agentcapable of converting the light of IR laser or the like into thermalenergy may be added to the recording layer or to any other layeradjacent to the recording layer. Having the constitution, theplanographic printing plate precursor of this embodiment enables imageformation through short time scanning exposure to laser light or thelike. Exposed to light in such a manner, the precursor has a hydrophobiclayer formed only in the exposed region of the image forming layer, andthe non-exposed region of the layer which essentially contains thehydrophilic resin remaining therein. In that condition, therefore, thenon-exposed region of the image forming layer in the precursor can bereadily removed by treating it with a small amount of water.Accordingly, the printing plate precursor of this embodiment realizesin-printer development merely requiring simple treatment with water ornot requiring any specific development, and it can be directly set in aprinter and processed into a printing plate therein. In the planographicprinting plate precursor of the present invention, a hydrophilic layerhaving a crosslinked structure which is obtained from organic/inorganiccomposite and a specific hydrophilic polymer, and an image forming layer(photosensitive or heat sensitive recording layer) may be formed in thatorder on a substrate.

A second aspect of the present invention is a substrate for aplanographic printing plate. The substrate comprises aluminum andincludes a hydrophilic surface formed by a hydrophilic polymer includinga functional group that chemically bonds to the aluminum substratedirectly or is chemically bindable to the aluminum substrate viastructural component having a crosslinking structure. The hydrophilicpolymer preferably includes the functional group as a terminal group.The hydrophilic surface may comprise a crosslinked structure formedthrough hydrolytic polycondensation of an alkoxide of an elementselected from Si, Ti, Zr and Al. It is also preferable that thehydrophilic surface comprises at least one of polymer compoundsrepresented by the general formulae (III) and (V). The polymer compoundrepresented by the general formula (III) is a polymer compoundcomprising the following units (i′) to (iii′), and a silane couplinggroup represented by unit (iii′) is a terminal end bounded to at leastone of the units (i′) and (ii′).

In the general formula (III), each of R¹, R², R³, R⁴, R⁵ and R⁶independently represents a hydrogen atom or a hydrocarbon group having 1to 8 carbon atoms; m is an integer of 0 to 2; x and y are numbersshowing a ratio of compositions when x+y=100, and a ratio of x toy=100:0 to 1:99; each of L¹, L² and L³ represent a single bond or anorganic linking group; each of Y¹ and Y² represents —N(R⁷) (R⁸), —OH,—NHCOR⁷—, —CO₂M—, or —SO₃M; each of R⁷ and R⁸ independently represents ahydrogen atom or an alkyl group having 1 to 8 carbon atoms; and Mrepresents one of a hydrogen atom, an alkali metal, an alkaline earthmetal and an onium.

The polymer compounds represented by the general formula (IV) comprisesunits (i″) and (ii″),

in the general formula (IV), each of R¹, R², R³, R⁴, R⁵ and R⁶independently represents a hydrogen atom or a hydrocarbon group having 1to 8 carbon atoms; m is an integer of 0 to 2; x and y are numbersshowing a ratio of compositions when x+y=100, and a ratio of x to y=99:1to 50:50; each of L¹ and L² represents a single bond or an organiclinking group; Y¹ represents t least one of —N(R⁷)(R⁸), —OH, —NHCOR⁷—,—CO₂M—, or —SO₃M; each of R⁷ and R⁸ independently represents a hydrogenatom or an alkyl group having 1 to 8 carbon atoms; and M represents oneof a hydrogen atom, an alkali metal, an alkaline earth metal and anonium. Preferably, the hydrophilic layer can be formed by preparing acoating liquid composition including the crosslinking componentrepresented by the general formula (II) and at least one of polymercompounds represented by the general formulae (III) and (IV), applyingthe coating liquid composition onto a surface of the substrate, anddrying the coating liquid composition. In this way, a hydrophilicsurface having a firm crosslinked structure can be easily formed. Thefunction of the second aspect of the present invention is not clear.However, it is supposed as follows. The polymer having a hydrophilicgroup has another reactive group that can be directly and chemicallybonded to the surface of the aluminum substrate, or that can chemicallybonded thereto through the constitutional component having a crosslinkedstructure. Therefore, the hydrophilic polymer is firmly bonded via thereactive group, which can cause a coupling reaction, to —Al³⁺ or —OH onthe surface of the aluminum substrate. On the other hand, thehydrophilic group does not participate in the bonding reaction to thesubstrate but is present in a relatively free state, and therefore, boththe firm bond and the high hydrophilicity are simultaneously realized.In a preferable embodiment, the hydrophilic group is adsorbed on thesubstrate through the crosslinked structure having a graft structure andformed by hydrolysis and polycondensation of an alkoxide compoundcontaining an element selected from Si, Ti, Zr and Al. Accordingly,hydrophilic functional groups introduced in the form of graft chains areunevenly distributed in a free state on the hydrophilic surface, and anorganic-inorganic composite film having a high density crosslinkedstructure is formed through hydrolysis and polycondensation of thealkoxide, whereby a film having high hydrophilicity and high strengthcan be obtained.

Third aspect of the present invention is a surface-hydrophilic membercomprising a substrate having disposed thereon a hydrophilic layer. Thehydrophilic layer includes hydrophilic graft chains and a crosslinkedstructure formed through hydrolytic polycondensation of an alkoxide ofan element selected from Si, Ti, Zr and Al. The hydrophilic layer of thethird aspect of the present invention can be formed in a same manner ofthe first aspect of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The planographic printing plate precursor, substrate for the same andsurface hydrophilic material of the present invention are described indetail hereinafter. In the present invention, the description of “formsimage forming” means that the image forming layer is formed on asubstrate, and the description does not exclude the presence of anyother layers, such as overcoat layer, undercoat layer, intermediatelayer and back coat layer that may be optionally formed on or in theprecursor in so far as those other layers do not detract the effect ofthe present invention.

First, hydrophilic polymer used for the substrate of the second aspectof the present invention is described below.

The specific hydrophilic polymer used herein is not particularly limitedas far as it has hydrophilic functional group, and further has reactivegroups on the terminal of the polymer chain or a side chain of thepolymer chain wherein the reactive groups are capable of forming achemical bond to the surface of the aluminum substrate directly orindirectly through the constitutional component having a crosslinkedstructure.

The specific hydrophilic polymer preferably has a crosslinking groupsuch as an alkoxyl group, as the reactive group. The polymer may bebonded to the substrate such that the crosslinking group is directlybonded to the functional group such as Al³⁺or a hydroxyl group, which ispresent on the surface of the aluminum substrate. Alternatively, it isalso possible that a crosslinked structure is formed through ahydrolysis and a polycondensation of the crosslinking group, and thepolymer is bonded to the substrate via the crosslinked structure. Thecrosslinked structure may be formed such that a hydrophilic coatingcomposition containing the specific hydrophilic polymer is prepared,coated on the surface of the aluminum substrate, and dried. In theinvention, hereinafter, the crosslinked structure formed by the latterprocess may be referred to as a “sol-gel crosslinked structure”.

Furthermore, the crosslinking group is preferably an alkoxide compoundcontaining an element selected from Si, Ti, Zr and Al, and an alkoxideof Si is preferable from the standpoint of their reactivity andavailability. That is, the crosslinking group may be formed from analkoxide compound. Specifically, alkoxide compounds, which are used as asilane coupling agent, are preferably used.

Preferable embodiments of the hydrophilic surface of the substrate ofthe present invention will be described below. Respective structures andthe forming methods for the hydrophilic surface are also described.

(Hydrophilic Polymer Having Reactive Group which Forms Chemical Bond toSurface of Aluminum Substrate Directly or Indirectly Via ConstitutionalComponent Having Crosslinked Structure)

The hydrophilic polymer chain wherein the polymer has reactive groupscapable of forming a chemical bond to the surface of the aluminumsubstrate directly or indirectly via the constitutional component havinga crosslinked structure, and reactive groups are provided onterminal-end or a side chain of the hydrophilic polymer chain (i.e., thespecific hydrophilic polymer) is not particularly limited as far as thepolymer has at least hydrophilicity and has the specific reactive groupin the molecule. Preferable embodiments thereof include polymer havingat least one of the structures of the following general formulae (III)and (IV).

(Specific hydrophilic Polymer Represented by General Formula (III))

The specific hydrophilic polymer represented by the following generalformula (III) (which will be sometimes referred to as a “specifichydrophilic polymer (III), hereinafter) is characterized by having asilane coupling group at an end.

The polymer compound represented by the formula (III) has the silanecoupling group represented by the structural unit (iii′) on at least oneof the both ends of the polymer, which are the polymer unit representedby the structural units (i′) and (ii′). The polymer compound may havethe functional group represented by the structural unit (iii′) onanother end position of the polymer, and may have a hydrogen atom or afunctional group having a capability to initiate polymerization.

In the general formula (III), m represents 0, 1 or 2, R¹, R², R³, R⁴, R⁵and R⁶ each independently represents a hydrogen atom or a hydrocarbongroup having 8 or less carbon atoms. Examples of the hydrocarbon groupinclude an alkyl group and aryl group, and a linear, branched or cyclicalkyl group having 8 or less carbon atoms is preferable. Specificexamples thereof include a methyl group, an ethyl group, a propyl group,a butyl group, a pentyl group, a hexyl group, a heptyl group, an octylgroup, an isopropyl group, an isobutyl group, a s-butyl group, a t-butylgroup, an isopentyl group, a neopentyl group, a 1-methylbutyl group, anisohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group and acyclopentyl group.

Each of R¹ to R⁶ is preferably a hydrogen atom, a methyl group or anethyl group from the standpoint of effect and availability.

The hydrocarbon group may be substituted.

In case where the alkyl group is substituted, the substituted alkylgroup is composed of a substituent and an alkylene group, and thesubstituent may be a monovalent non-metallic atomic group excepthydrogen. Preferable examples of the substituent include a halogen atom(—F, —Br, —Cl, —I), a hydroxyl group, an alkoxy group, an aryloxy group,a mercapto group, an alkylthio group, an arylthio group, an alkyldithiogroup, an aryldithio group, an amino group, an N-alkylamino group, anN,N-diarylamino group, an N-alkyl-N-arylamino group, an acyloxy group, acarbamoyloxy group, an N-alkylcarbamoyloxy group, an N-arylcarbamoyloxygroup, an N,N-dialkylcarbamoyloxy group, an N,N-diarylcarbamoyloxygroup, an N-alkyl-N-arylcarbamoyloxy group, an alkylsulfoxy group, anarylsulfoxy group, an acylthio group, an acylamino group, anN-alkylacylamino group, an N-arylacylamino group, an ureido group, anN-alkylureido group, an N′,N′-dialkylureido group, an N′-arylureidogroup, an N′,N′-diarylureido group, an N′-alkyl-N′-arylureido group, anN-alkylureido group, an N-arylureido group, an N′-alkyl-N-alkylureidogroup, an N′-alkyl-N-arylureido group, an N′,N′-dialkyl-N-alkylureidogroup, an N′,N′-dialkyl-N-arylureido group, an N′-aryl-N-alkylureidogroup, an N′-aryl-N-arylureido group, an N′,N′-diaryl-N-alkylureidogroup, an N′,N′-diaryl-N-arylureido group, anN′-alkyl-N′-aryl-N-alkylureido group, an N′-alkyl-N′-aryl-N-arylureidogroup, an alkoxycarbonylamino group, an aryloxycarbonylamino group, anN-alkyl-N-alkoxycarbonylamino group, an N-alkyl-N-aryloxycarbonylaminogroup, an N-aryl-N-alkoxycarbonylamino group, anN-aryl-N-aryloxycarbonylamino group, a formyl group, an acyl group, acarboxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, acarbamoyl group, an N-alkylcarbamoyl group, an N,N-dialkylcarbamoylgroup, an N-arylcarbamoyl group, an N,N-diarylcarbamoyl group, anN-alkyl-N-arylcarbamoyl group, an alkylsulfinyl group, an arylsulfinylgroup, an alkylsulfonyl group, an arylsulfonyl group, a sulfo group(—SO₃H) and its conjugated base group (hereinafter referred to as asulfonato group), an alkoxysulfonyl group, an aryloxysulfonyl group, asulfinamoyl group, an N-alkylsulfinamoyl group, anN,N-dialkylsulfinamoyl group, an N-arylsulfinamoyl group, anN,N-diarylsulfinamoyl group, an N-alkyl-N-arylsulfinamoyl group, asulfamoyl group, an N-alkylsulfamoyl group, an N,N-dialkylsulfamoylgroup, an N-arylsulfamoyl group, an N,N-diarylsulfamoyl group, anN-alkyl-N-arylsulfamoyl group, a phosphono group (—PO₃H₂) and itsconjugated base group (hereinafter referred to as a phosphonato group),a dialkylphosphono group (—PO₃(alkyl)₂), a diarylphosphono group(—PO₃(aryl)₂), an alkylarylphosphono group (—PO₃(alkyl)(aryl)), amonoalkylphosphono group (—PO₃H(alkyl)) and its conjugated base group(hereinafter referred to as an alkylphosphonato group), amonoarylphosphono group (—PO₃H(aryl)) and its conjugated base group(hereinafter referred to as an arylphosphonato group), a phosphonoxygroup (—OPO₃H₂) and its conjugated base group (hereinafter referred toas a phosphonatoxy group), a dialkylphosphonoxy group (—OPO₃(alkyl)₂), adiarylphosphonoxy group (—OPO₃(aryl)₂), an alkylarylphosphonoxy group(—OPO₃(alkyl) (aryl)), a monoalkylphosphonoxy group (—OPO₃H(alkyl)) andits conjugated base group (hereinafter referred to as analkylphosphonatoxy group), a monoarylphosphonoxy group (—OPO₃H(aryl))and its conjugated base group (hereinafter referred to as anarylphosphonatoxy group), a morpholino group, a cyano group, a nitrogroup, an aryl group, an alkenyl group, and an alkynyl group.

As examples of the alkyl group comprised in the substituent, those alkylgroups mentioned above are included. Examples of the aryl group comprisephenyl, biphenyl, naphthyl, tolyl, xylyl, mesityl, cumenyl,chlorophenyl, bromophenyl, chloromethylphenyl, hydroxyphenyl,methoxyphenyl, ethoxyphenyl, phenoxyphenyl, acetoxyphenyl,benzoyloxyphenyl, methylthiophenyl, phenylthiophenyl, methylaminophenyl,dimethylaminophenyl, acetylaminophenyl, carboxyphenyl,methoxycarbonylphenyl, ethoxycarbonylphenyl, phenoxycarbonylphenyl,N-phenylcarbamoylphenyl, phenyl, cyanophenyl, sulfophenyl,sulfonatophenyl, phosphonophenyl and phosphonatophenyl groups. Examplesof the alkenyl group include vinyl, 1-propenyl, 1-butenyl, cinnamyl and2-chloro-1-ethenyl groups. Examples of the alkynyl group includeethynyl, 1-propynyl, 1-butynyl and trimethylsilylethynyl groups.Examples of G¹ in the acyl group (G¹CO—) includes a hydrogen atom, analkyl group and an aryl group such as those mentioned above.

Of those substituents, more preferable examples include a halogen atom(—F, —Br, —Cl, —I), an alkoxy group, an aryloxy group, an alkylthiogroup, an arylthio group, an N-alkylamino group, an N,N-dialkylaminogroup, an acyloxy group, an N-alkylcarbamoyloxy group, anN-arylcarbamoyloxy group, an acylamino group, a formyl group, an acylgroup, a carboxyl group, an alkoxycarbonyl group, an aryloxycarbonylgroup, a carbamoyl group, an N-alkylcarbamoyl group, anN,N-dialkylcarbamoyl group, an N-arylcarbamoyl group, anN-alkyl-N-arylcarbamoyl group, a sulfo group, a sulfonato group, asulfamoyl group, an N-alkylsulfamoyl group, an N,N-dialkylsulfamoylgroup, an N-arylsulfamoyl group, an N-alkyl-N-arylsulfamoyl group, aphosphono group, a phosphonato group, a dialkylphosphono group, adiarylphosphono group, a monoalkylphosphono group, an alkylphosphonatogroup, a monoarylphosphono group, an arylphosphonato group, aphosphonoxy group, a phosphonatoxy group, an aryl group, and an alkenylgroup.

The alkylene group contained in the substituted alkyl group may be adivalent organic residue derived from the above-mentioned alkyl grouphaving 1 to 20 carbon atoms by removing any one hydrogen atom from it.Preferably, it is a linear alkylene group having from 1 to 12 carbonatoms, or a branched alkylene group having from 3 to 12 carbon atoms, ora cyclic alkylene group having from 5 to 10 carbon atoms. Combining thesubstituent with the alkylene group gives a substituted alkyl group.Preferable examples of the substituted alkyl group include chloromethyl,bromomethyl, 2-chloroethyl, trifluoromethyl, methoxymethyl,methoxyethoxyethyl, allyloxymethyl, phenoxymethyl, methylthiomethyl,tolylthiomethyl, ethylaminoethyl, diethylaminopropyl, morpholinopropyl,acetyloxymethyl, benzoyloxymethyl, N-cyclohexylcarbamoyloxyethyl,N-phenylcarbamoyloxyethyl, acetylaminoethyl, N-methylbenzoylaminopropyl,2-hydroxyethyl, 2-hydroxypropyl, carboxypropyl, methoxycarbonylethyl,allyloxycarbonylbutyl, chlorophenoxycarbonylmethyl, carbamoylmethyl,N-methylcarbamoylethyl, N,N-dipropylcarbamoylmethyl,N-(methoxyphenyl)carbamoylethyl, N-methyl-N-(sulfonyl)carbamoylmethyl,sulfobutyl, sulfonatobutyl, sulfamoylbutyl, N-ethylsulfamoylmethyl,N,N-dipropylsulfamoylpropyl, N-tolylsulfamoylpropyl,N-methyl-N-(phosphonophenyl)sulfamoyloctyl, phosphonobutyl,phosphonatohexyl, diethylphosphonobutyl, diphenylphosphonopropyl,methylphosphonobutyl, methylphosphonatobutyl, tolylphosphonohexyl,tolylphosphonatohexyl, phosphonoxypropyl, phosphonatoxybutyl, benzyl,phenethyl, α-methylbenzyl, 1-methyl-1-phenylethyl, p-methylbenzyl,cinnamyl, allyl, 1-propenylmethyl, 2-butenyl, 2-methylallyl,2-methylpropenylmethyl, 2-propynyl, 2-butynyl, and 3-butynyl groups.

Each of L¹ and L² represents a single bond or an organic linking group.The organic linking group herein means a polyvalent linking group formedwith non-metallic atoms. Concretely, it is composed of from 1 to 60carbon atoms, from 0 to 10 nitrogen atoms, from 0 to 50 oxygen atoms,from 1 to 100 hydrogen atoms and from 0 to 20 sulfur atoms. Morespecific examples of the linking group include the following structuralunits and those constituted with a combination thereof.

L³ represents a single bond or an organic linking group. The organiclinking group herein means a polyvalent linking group of non-metallicatoms, and specific examples thereof include those similar to L¹ and L².Among these, —(CH₂)_(n)—S—(wherein n is an integer of from 1 to 8) is aparticularly preferable.

Y represents —NHCOR⁵, —CONH₂, —CON(R⁵)₂, —COR⁵, —OH, —CO₂M or —SO₃M; andR⁵ represents a linear, branched or cyclic alkyl group having from 1 to8 carbon atoms. R⁵'s such as those included in —CON(R⁵)₂ may bond toeach other to form a ring, and the ring thus formed may be a hetero ringcontaining hetero atom(s) of, for example, oxygen, sulfur and nitrogenatoms. R⁵ may be substituted. As examples of the substituent for it,those mentioned above as the substituent for the alkyl group for R¹, R²,R³ and R⁴ are usable and referred to.

Concretely, preferable examples of R⁵ include methyl, ethyl, propyl,butyl, pentyl, hexyl, heptyl, octyl, isopropyl, isobutyl, s-butyl,t-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl,2-methylhexyl and cyclopentyl groups.

Examples of M include a hydrogen atom, an alkali metal such as lithium,sodium or potassium, an alkaline earth metal such as calcium or barium,or an onium such as ammonium, iodonium and sulfonium.

Concretely, preferable examples of Y include —NHCOCH₃, —CONH₂, —COOH,—SO₃ ⁻NMe₄ ⁺, and a morpholino group.

Further, x and y represent a compositional ratio where x+y=100, and x/yis in a range of from 100/0 to 1/99 and more preferably from 100/0 to5/95.

The molecular weight of the specific hydrophilic polymer (III) ispreferably from 1,000 to 100,000, more preferably from 1,000 to 50,000,and most preferably from 1,000 to 30,000.

Examples of the specific hydrophilic polymer (III) (Compound 1-1 toCompound 1-23) preferable for use in the present invention are mentionedbelow, to which, however, the present invention is not limited.

(Synthesis Method)

The specific hydrophilic polymer (III) in the present invention can besynthesized by radical polymerization of a radically polymerizablemonomer represented by the following structural units (i′) and (ii′),and the following structural unit (iii′) which is a silane couplingagent having a chain transfer function for the radical polymerization.Owing to the chain transfer function of the silane coupling agent, apolymer having a silane coupling group which is introduced on the end ofthe polymer main chain can be synthesized through the radicalpolymerization.

The reaction mode thereof is not particularly limited. For example, abulk reaction, a solution reaction or a suspension reaction may becarried out in the presence of a radical polymerization initiator orunder irradiation with a high-pressure mercury lamp.

When the polymerization reaction is carried out, in order to control theintroduced amount of the structural unit represented by (iii′) and tosuppress polymerization of unit (iii′) with the structural unit (i′) or(ii′) in an effective manner, it is preferable that a polymerizationmethod such as a divided addition method, a sequential addition methodof the unsaturated compound is carried out.

The reaction ratio of the structural units (i′) and (ii′) with respectto the structural unit (iii′) is not particularly limited. However, itis preferable that the amount of the structural units (i′) and (ii′) isin a range of from 0.5 to 50 mole per 1 mole of the structural unit(iii′), from the standpoint of a suppression of side reactions and animprovement in yield of the hydrolyzable silane compound. It is morepreferably in a range of from 1 to 45 mole, and most preferably in arange of from 5 to 40 mole.

In the structural units (i′), (ii′) and (iii′), R¹ to R⁶, L¹ to L³, Y¹,Y² and m have the same meanings as in the general formula (III). Thesecompounds are commercially available and can be easily synthesized.

For forming the specific hydrophilic polymer (III), general radicalpolymerization methods are usable. Concretely, those described in ShinKobunshi Jikken-gaku 3 (New Polymer Experimentation 3), Kobunshi noGousei to Hannou 1 (Synthesis and Reaction of Polymers 1), (edited byPolymer Society Japan, Kyoritsu Shuppan Co., Ltd.), Shin Jikken KagakuKouza 19 (Lectures on New Experimental Chemistry 19), Kobunshi Kagaku(I) (Polymer Chemistry (I)), (edited by The Chemical Society of Japan,Maruzen) and Busshitu Kougaku Kouza (Lectures on Substance Engineering),Kobunshi Gousei Kagaku (Synthetic Polymer Chemistry), (PublishingDivision of Tokyo Denki University), which can be applied thereto.

The specific hydrophilic polymer (III) may be a copolymer with othermonomers described later. Examples of the other monomers include knownmonomers, such as acrylate esters, methacrylate esters, acrylamides,methacrylamides, vinyl esters, styrenes, acrylic acid, methacrylic acid,acrylonitrile, maleic anhydride and maleimide. Various properties, suchas film forming property, film strength, hydrophilicity, hydrophobicity,solubility, reactivity and stability, can be improved by copolymerizingthe monomers selected.

Specific examples of the acrylate esters include methyl acrylate, ethylacrylate, (n- or i-) propyl acrylate, (n-, i-, sec- or t-) butylacrylate, amyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate,chloroethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,2-hydroxypentyl acrylate, cyclohexyl acrylate, allyl acrylate,trimethylolpropane monoacrylate, pentaerythritol monoacrylate, benzylacrylate, methoxybenzyl acrylate, chlorobenzyl acrylate, hydroxybenzylacrylate, hydroxyphenethyl acrylate, dihydroxyphenethyl acrylate,furfuryl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate,hydroxyphenyl acrylate, chlorophenyl acrylate, sulfamoylphenyl acrylateand 2-(hydroxyphenylcarbonyloxy)ethyl acrylate.

Specific examples of the methacrylate esters include methylmethacrylate, ethyl methacrylate, (n- or i-) propyl methacrylate, (n-,i-, sec- or t-) butyl methacrylate, amyl methacrylate, 2-ethylhexylmethacrylate, dodecyl methacrylate, chloroethyl methacrylate,2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate,2-hydroxypentyl methacrylate, cyclohexyl methacrylate, allylmethacrylate, trimethylolpropane monomethacrylate, pentaerythritolmonomethacrylate, benzyl methacrylate, methoxybenzyl methacrylate,chlorobenzyl methacrylate, hydroxybenzyl methacrylate, hydroxyphenethylmethacrylate, dihydroxyphenethyl methacrylate, furfuryl methacrylate,tetrahydrofurfuryl methacrylate, phenyl methacrylate, hydroxyphenylmethacrylate, chlorophenyl methacrylate, sulfamoylphenyl methacrylateand 2-(hydroxyphenylcarbonyloxy)ethyl methacrylate.

Specific examples of the acrylamides include acrylamide,N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide,N-butylacrylamide, N-benzylacrylamide, N-hydroxyethylacrylamide,N-phenylacrylamide, N-tolylacrylamide, N-(hydroxyphenyl)acrylamide,N-(sulfamoylphenyl)acrylamide, N-(phenylsulfonyl)acrylamide,N-(tolylsulfonyl)acrylamide, N,N-dimethylacrylamide,N-methyl-N-phenylacrylamide and N-hydroxyethyl-N-methylacrylamide.

Specific examples of the methacrylamides include methacrylamide,N-methylmethacrylamide, N-ethylmethacrylamide, N-propylmethacrylamide,N-butylmethacrylamide, N-benzylmethacrylamide,N-hydroxyethylmethacrylamide, N-phenylmethacrylamide,N-tolylmethacrylamide, N-(hydroxyphenyl)methacrylamide,N-(sulfamoylphenyl)methacrylamide, N-(phenylsulfonyl)methacrylamide,N-(tolylsulfonyl)methacrylamide, N,N-dimethylmethacrylamide,N-methyl-N-phenylmethacrylamide and N-hydroxyethyl-N-methylmethacrylamide.

Specific examples of the vinyl esters include vinyl acetate, vinylbutyrate and vinyl benzoate.

Specific examples of the styrenes include styrene, methylstyrene,dimethylstyrene, trimethylstyrene, ethylstyrene, propylstyrene,cyclohexylstyrene, chloromethylstyrene, trifluoromethylstyrene,ethoxymethylstyrene, acetoxymethylstyrene, methoxystyrene,dimethoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene,iodostyrene, fluorostyrene and carboxystyrene.

An amount of the other monomers used for synthesizing the copolymer isan amount that is sufficient to improve the various properties. However,when the amount thereof is too large, the function as a support for aplanographic printing plate becomes insufficient. Therefore, thepreferable total ratio of the other monomers in the specific hydrophilicpolymer (III) is preferably 80% by weight or less, and more preferably50% by weight or less.

(Specific Hydrophilic Polymer Represented by General Formula (IV))

The specific hydrophilic polymer represented by the following generalformula (IV) (which may be referred to as a “specific hydrophilicpolymer (IV), hereinafter) is characterized by having a silane couplinggroup on a side chain.

In the general formula (IV), m, R¹ to R⁶, L¹, L² and Y¹ have the samemeanings as in the general formula (III).

x and y represent a compositional ratio wherein x+y=100, and x/y is in arange of from 99:1 to 50:50, preferably from 99:1 to 60:40, and morepreferably from 98:2 to 70:30.

The molecular weight of the specific hydrophilic polymer (IV) ispreferably from 1,000 to 100,000, and more preferably from 1,000 to50,000.

Specific examples (2-1) to (2-7) of the specific hydrophilic polymer(IV) that can be preferably used in the invention will be describedbelow, but the invention is not limited to them.

(Synthesis Method)

As a radical polymerization method for synthesizing the specifichydrophilic polymer (IV), all the known methods may be used.Specifically, the general radical polymerization methods described, forexample, in Shin Kobunshi Jikken-gaku 3 (New Polymer Experimentation 3),Kobunshi no Gousei to Hannou 1 (Synthesis and Reaction of Polymers 1),(edited by Polymer Society Japan, Kyoritsu Shuppan Co., Ltd.), ShinJikken Kagaku Kouza 19 (Lectures on New Experimental Chemistry 19),Kobunshi Kagaku (I) (Polymer Chemistry (I)), (edited by The ChemicalSociety of Japan, Maruzen) and Busshitu Kougaku Kouza (Lectures onSubstance Engineering), Kobunshi Gousei Kagaku (Synthetic PolymerChemistry), (Publishing Division of Tokyo Denki University) can beapplied thereto.

The specific hydrophilic polymer (IV) may be a copolymer obtained byusing other monomers in addition to the units, and as the othermonomers, monomers those mentioned in the specific hydrophilic polymer(III) may be used.

(Crosslinking Component Represented by General Formula (II))

The hydrophilic surface of the second aspect of the present inventionmay be formed in such a manner that the crosslinking group in thespecific hydrophilic polymer is directly bonded to the functional groupon the surface of the aluminum substrate, or in alternative, ahydrophilic coating composition containing the specific hydrophilicpolymer is prepared and coated on the surface of the aluminum substrate,followed by drying, so as to form a crosslinked structure (sol-gelcrosslinked structure) through hydrolysis and polycondensation of thecrosslinking group.

For forming the sol-gel crosslinked structure, it is preferred that thespecific hydrophilic polymer and the crosslinking component representedby the aforementioned general formula (II) are mixed and coated on thesurface of the substrate, followed by drying. The crosslinking componentrepresented by the general formula (II) is a compound having apolymerizable functional group in the structure thereof and exhibitingthe function as a crosslinking agent, and it forms a firm film having acrosslinked structure through polycondensation with the specifichydrophilic polymer. Details of the crosslinking components representedby the general formula (II) are described herein after.

(A) Hydrophilic Layer:

In the first and third aspect of the present invention, the hydrophiliclayer thereof has hydrophilic graft chains and has a crosslinkedstructure formed through hydrolytic polycondensation of an alkoxide withany of Si, Ti, Zr and Al. The crosslinked hydrophilic layer may beformed from an alkoxide mentioned above and a compound having ahydrophilic functional group capable of forming hydrophilic graftchains, in any desired manner. In view of reactivity and easyavailability thereof, a Si alkoxide is preferab. Concretely, compoundsknown for silane coupling agents are favorable as the alkoxide of Si.

The crosslinked structure formed through hydrolytic polycondensation ofthe alkoxide may be hereinafter referred to as a sol-gel crosslinkedstructure.

Preferably, the hydrophilic layer that comprises the free hydrophilicgraft chains and the sol-gel crosslinked structure contains ahydrophilic polymer described in detail hereinafter.

The constituent components of preferable embodiments of the hydrophiliclayer in the present invention, and the method of forming thehydrophilic layer are described in detail below.

1. Polymer Compound of Formula (I):

The polymer compound represented by the formula (I) is a hydrophilicpolymer terminated with a silane coupling group, namely, the polymercompound has a silane coupling group as an end group, and this compoundwill be referred to as a specific hydrophilic polymer.

In formula (I), R¹, R², R³ and R⁴ each independently represent ahydrogen atom or a hydrocarbon group having at most 8 carbon atoms. Thehydrocarbon group includes, for example, an alkyl group and an arylgroup, and is preferably a linear, branched or cyclic alkyl group havingat most 8 carbon atoms. Concretely, examples thereof include methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, isopropyl, isobutyl,s-butyl, t-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl,2-ethylhexyl, 2-methylhexyl and cyclopentyl groups.

In view of the effect and the easy availability of the compound, R¹, R²,R³ and R⁴ are preferably a hydrogen atom, or a methyl or ethyl group.The alkyl group (hydrocarbon group) may be substituted, and examples andthe like of the substituent and alkylene group are the same of those ofthe hydrocarbon having 1 to 8 carbon atoms of the polymer compoundrepresented by the general formula (III).

In the general formula (I), L represents a single bond or an organiclinking group. When L represents an organic linking group, it is apolyvalent linking group of non-metallic atoms. Concretely, it iscomposed of from 1 to 60 carbon atoms, from 0 to 10 nitrogen atoms, from0 to 50 oxygen atoms, from 1 to 100 hydrogen atoms, and from 0 to 20sulfur atoms. Concrete examples of the linking group include thestructural units and a combination thereof mentioned above as examplesof structural unit for L¹ and L² of the general formula (III).

Examples of the specific hydrophilic polymer (Compound 3-1 to Compound3-12) preferable for use in the present invention are mentioned below,to which, however, the present invention is not limited.

The specific hydrophilic polymer for use in the first and third aspectof the present invention can be produced through radical polymerizationof a radical-polymerizable monomer of the following general formula (i)with a silane coupling agent of the following general formula (ii) whichacts as a chain-transfer agent in radical polymerization. Since thesilane coupling agent (ii) has the ability to act as a chain-transferagent, the radical polymerization gives a polymer terminated with asilane-coupling agent introduced thereinto.

(R¹)_(m)(OR²)_(3−m)—Si—(CH₂)_(n)—S—H  (ii)

In formulae (i) and (ii), R¹ to R⁴, L, Y, n and m have the same meaningsas those in formula (I). These compounds are on the market, and can beeasily produced.

The radical polymerization to produce the hydrophilic polymer of formula(I) may be effected in any known manner. Concretely, general methods ofradical polymerization are described in, for example, New PolymerExperimentation 3, Polymer Synthesis and Reaction 1 (edited by thePolymer Society of Japan, published by Kyoritsu Publishing); NewExperimental Chemistry Course 19, Polymer Chemistry (I) (edited by theChemical Society of Japan, published by Maruzen); Material EngineeringCourse, Polymer Synthesis Chemistry (published by the Tokyo ElectricCourage Publishing), and any of these are employable herein.

2. Crosslinking Component of Formula (II):

The crosslinking component represented by the formula (II) is a compoundhaving a polymerizing functional group in its structure and acts as acrosslinking agent. By polycondensing with the specific hydrophilicpolymer mentioned above, the compound forms a tough film having acrosslinked structure.

In formula (II), R⁶ represents a hydrogen atom, an alkyl group or anaryl group; R⁷ represents an alkyl group or an aryl group; X representsSi, Al, Ti or Zr; and m indicates an integer of from 0 to 2.

The alkyl group for R⁶ and R⁷ preferably has from 1 to 4 carbon atoms.The alkyl group and the aryl group for these may be substituted. Thesubstituent for the groups includes, for example, a halogen atom, anamino group and a mercapto group.

The compound is a low-molecular compound, and preferably has a molecularweight of at most 1000.

Examples of the crosslinking component of formula (II) are mentionedbelow, to which, however, the present invention is not limited.

Examples of the compound in which X is Si, namely silicon-containinghydrolyzable compounds, include trimethoxysilane, triethoxysilane,tripropoxysilane, tetramethoxysilane, tetraethoxysilane,tetrapropoxysilane, methyltrimethoxysilane, ethyltriethoxysilane,propyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane,propyltriethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane,γ-chloropropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane,γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane,phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane,diphenyldimethoxysilane, and diphenyldiethoxysilane.

Of those, especially preferable examples thereof includetetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane,ethyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane,dimethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane,diphenyldimethoxysilane, and diphenyldiethoxysilane.

Examples of the compound in which X is Al, aluminium-containinghydrolyzable compounds, include trimethoxyaluminate, triethoxyaluminate,tripropoxyaluminate, and tetraethoxyaluminate.

Examples of the compound in which X is Ti, namely titanium-containingcompounds, include trimethoxytitanate, tetramethoxytitanate,triethoxytitanate, tetraethoxytitanate, tetrapropoxytitanate,chlorotrimethoxytitanate, chlorotriethoxytitanate,ethyltrimethoxytitanate, methyltriethoxytitanate,ethyltriethoxytitanate, diethyldiethoxytitanate,phenyltrimethoxytitanate, and phenyltriethoxytitanate.

Examples of the compound in which X is Zr, namely zirconium-containingcompounds, are zirconates corresponding to the titanium-containingcompounds but containing zirconium in place of titanium.

3. Formation of Hydrophilic Layer:

In the present invention, the hydrophilic layer may be formed bypreparing a hydrophilic coating liquid composition that contains aspecific hydrophilic polymer, applying the liquid onto a suitablesubstrate, and drying it. In the hydrophilic coating liquid composition,the content of the specific hydrophilic polymer is preferably notsmaller than 10% by weight but smaller than 50% by weight based on thetotal solid content of the layer. If the polymer content is 50% byweight or more, the strength of the film formed will lower; but ifsmaller than 10% by weight, the film properties will be not good and thefilm will be readily cracked. Therefore, these contents are unfavorable.

In one preferable embodiment of the present invention, the crosslinkingcomponent is added to the hydrophilic coating liquid composition. Inthis case, the amount of the crosslinking component to be added ispreferably 5 mol % or more, more preferably 10 mol % or more withrespect to the silane-coupling group in the specific hydrophilicpolymer. The uppermost limit of the amount of the crosslinking componentis not specifically defined so far as it ensures good crosslinking ofthe component with the hydrophilic polymer. However, if the amount ofthe crosslinking component added is too large, it will be problematic inthat the excess crosslinking component not having acted in crosslinkingwill make the surface of the formed hydrophilic layer sticky.

The specific hydrophilic polymer terminated with silane coupling groupis dissolved in a solvent, preferably along with the crosslinkingcomponent, and well stirred, and these are hydrolyzed and polycondensedto prepare an organic/inorganic composite sol. This is the hydrophiliccoating liquid for use in the present invention, and this forms asurface hydrophilic layer of high hydrophilicity and high film strength.To promote the hydrolysis and polycondensation in preparing theorganic/inorganic composite sol, an acid catalyst or a basic catalyst ispreferably used. For increasing the reaction efficiency in practice, thecatalyst is indispensable.

As the catalyst, an acid or a basic compound itself or those dissolvedin a solvent of water or alcohol may be used. These acid and basiccompounds will be hereinafter referred to as an acid catalyst and abasic catalyst, respectively. The catalyst concentration in the solventis not specifically defined, and may be suitably determined depending onthe properties of the acid or the basic compound used and on the desiredcontent of the catalyst in the reaction system. The catalyst solution ofhigher concentration can promote the hydrolysis and the polycondensationof the system. However, if the basic catalyst of high concentration isused, a precipitate is formed in the sol. Therefore, the concentrationof the basic catalyst is preferably at most 1 N in terms of theconcentration of the catalyst in the aqueous solution.

The acid catalyst and the basic catalyst for use herein are notspecifically limited in point of their type. However, if the catalyst isused in high concentration, compound wherein elements that will remainlittle in the dried film are comprised is preferable as the catalyst.

Concretely, examples of the acid catalyst includes hydrogen halides suchas hydrochloric acid; nitric acid, sulfuric acid, sulfurous acid,hydrogen sulfide, perchloric acid, hydrogen peroxide, carbonic acid;carboxylic acids such as formic acid and acetic acid; substitutedcarboxylic acids of formula RCOOH in which R is substituted with anyother element or substituent; and sulfonic acids such as benzenesulfonicacid. Examples of the basic catalyst include ammonia bases such asaqueous ammonia, and amines such as ethylamine and aniline.

To prepare the hydrophilic coating liquid, the silane couplinggroup-terminated hydrophilic polymer is dissolved in a solvent such asethanol, preferably along with the crosslinking component, andoptionally the catalyst described above is added thereto, and themixture is stirred. Preferably, the reaction temperature is between roomtemperature and 80° C., and the reaction time for which the mixture isstirred is between 1 and 72 hours. Stirring the mixture promotes thehydrolysis and polycondensation of the two components to give theintended organic/inorganic composite sol.

The solvent usable for preparing the hydrophilic coating liquidcomposition that contains the hydrophilic polymer, preferably along withthe crosslinking component, is not specifically limited in so far as thesolvent can uniformly dissolve and disperse the components. For example,the solvent is preferably an aqueous solvent such as methanol, ethanoland water.

As mentioned above, the organic/inorganic composite sol, which is sol ofcomposite comprising organic and inorganic compounds, (hydrophiliccoating liquid composition) to form the hydrophilic surface in thepresent invention can be prepared in a sol-gel method. The sol-gelmethod is described in detail, for example, in Sumio Sakuhana's Sciencefor Sol-Gel Process (published by Agune Shofusha, 1988); and KenHirashima's Technology for Functional Thin film Formation by LatestSol-Gel Process (published by General Technology Center, 1992). Themethods described in these can be employed in preparing the hydrophiliccoating liquid composition for use in the present invention.

The hydrophilic coating liquid composition used in the present inventionmay contain, if desired, various additives in so far as it does notinterfere the effect of the present invention. For example, a surfactantmay be added thereto for improving the uniformity of the coating liquid.

The hydrophilic coating liquid composition prepared in the manner asdescribed above is applied onto the surface of a substrate and dried toform thereon the intended hydrophilic layer. The thickness of thehydrophilic layer may be determined in any desired value, but dry weightof the layer is generally from 0.5 to 5.0 g/m², preferably from 1.0 to3.0 g/m². If the thickness of the layer is smaller than 0.5 g/m², it isunfavorable since the layer could not well hydrophilicate the substratesurface; but if larger than 5.0 g/m², it is also unfavorable since thesensitivity and the film strength will lower.

(B) Image Forming Layer

On the hydrophilic surface of the support for a planographic printingplate of first and second aspect of the invention, a predeterminedrecording layer (image forming layer) is formed, whereby a planographicprinting plate precursor is obtained. Any image forming layer may beformed optionally. If necessary, image forming layer may be formed onthe hydrophilic surface of the material of the third aspect of thepresent invention. Some representative examples of image forming layerare described below.

(Photosensitive or Heat-sensitive Image Forming Layer)

In the first and second aspect of the present invention, at least one ofimage forming layer is formed on the hydrophilic layer to form aplanographic printing plate precursor. The substrate and precursor ofthe first and second aspect of the present invention has a surfaceexcellent in hydrophilicity, and therefore, an image having excellentimage quality without contamination on the non-image portion can beformed eve if any image forming layer is formed.

The image forming layer provided on the hydrophilic surface is optional.However, preferable examples thereof include a photosensitive layer anda heat-sensitive layer wherein the image forming layer containing aknown positive sensitive composition or a known negative sensitivecomposition.

(Positive Sensitive Composition)

As the positively sensitive composition used in the image forming layerin the present invention, it is preferable to use the known positivesensitive compositions (a) and (b) shown below.

(a) A conventional positive photosensitive composition containingnaphthoquinone diazide and a novolak resin

(b) A chemical sensitized positive photosensitive composition containinga combination of an alkali soluble compound protected with anacid-decomposable group and an acid generator

The compositions (a) and (b) are well known in this field of art, and itis more preferable that they be used in combination with the followingpositively sensitive compositions (c) to (f).

(c) A laser-sensitive positive composition which contains a sulfonatepolymer and an infrared ray absorbent, and is capable of forming aplanographic printing plate without developing treatment disclosed inJP-A No. 10-282672

(d) A laser-sensitive positive composition which contains a carboxylatepolymer and an acid generator or an infrared ray absorbent, and iscapable of forming a planographic printing plate without developingtreatment disclosed in EP No. 652,483 and JP-A No. 6-502260

(e) A laser-sensitive positive composition which contains an alkalisoluble compound and a substance that is heat-decomposable andsubstantially decreases the solubility of the alkali soluble compoundwhen the substance does not decomposed disclosed in JP-A No. 11-95421

(f) An alkali-developable elution type positive composition whichcontains an infrared ray absorbent, a novolak resin and a dissolutionpreventing agent, and is capable of forming an alkali-developableelusion type positive printing plate

These positive sensitive compositions have a function such thatsuppressing effect with respect to dissolution into the developer suchas an alkali aqueous solution is cancelled by applying energy to form anon-image part.

The alkali soluble compound used in the positive sensitive compositionas a main component is a compound that, in the case where it is appliedto a positive material, alkali solubility thereof is lowered in thepresence of a dissolution preventing agent, and the alkali solubility isrecovered by decomposition of the dissolution preventing compound.Examples of the alkali soluble compound used in the positively sensitivecomposition include a novolak resin, polyhydroxystyrene and an acrylicresin.

A solubility preventing agent may be added to the alkali solublecompound. The solubility preventing agent is such a compound that isdecomposed by an action of an acid and becomes alkali soluble. Examplesof the dissolution preventing agent include a carboxylic acid, a phenolcompound and a quinone diazide compound that are protected with an aciddecomposable group of a chemical sensitizing type used in the field ofresists, such as a t-butyl ester, t-butyl carbamate and an alkoxyethylester.

An acid generator, which is a compound generating an acid by heat orlight, also be usable for canceling the dissolution suppressing effect.

(Negative Sensitive Composition)

As the negative sensitive composition, the known negative sensitivecompositions (g) to (j) shown below can be used in the presentinvention.

(g) A negative sensitive composition containing a polymer having aphoto-crosslinkable group and an azide compound

(h) A negative sensitive composition containing a diazo compounddisclosed in JP-A No. 59-101651

(i) A photopolymerizable negatively sensitive composition containing aphotopolymerization initiator and an addition polymerizable unsaturatedcompound disclosed in U.S. Pat. No. 5,262,276 and JP-A No. 2-63054

(j) A negatively sensitive composition containing an alkali solublecompound, an acid generator and an acid crosslinkable compound disclosedin JP-A No. 11-95421

The negative sensitive composition is such a composition that formationof a crosslinked structure and/or a polymerization reaction occurs andproceeds in the composition due to application of energy, whereby thecomposition is hardened to form an image part.

Examples of the major hardening reactions include a reaction wherein apolymer having a photocrosslinkable group, such as a polymer having—CH═CH—CO— as a photocrosslinkable group on the main chain or the sidechain of the molecule, forms a crosslinked structure by exposure tolight and hardened, a hardening reaction using an azide compound and adiazo compound, a hardening reaction wherein the composition contains aphotopolymerization initiator and an addition polymerizable unsaturatedcompound having two or more terminal-ethylenically groups, andpolymerization proceeds by exposure to light, and a reaction wherein thecompound contains an acid generator and a compound capable of beingcrosslinked in the presence of an acid, such as a reaction wherein anacid crosslinkable compound such as an aromatic compound and aheterocyclic compound having been polysubstituted with a hydroxymethylgroup, an acetoxymethyl group or an alkoxymethyl group are used, and acrosslinked structure is formed by application of energy.

The negatively sensitive composition may contain the alkali solublecompound similar to those used in the positively sensitive compound inorder to improve the film property.

(B-1) Especially Preferable Image Forming Layer of the PresentInvention:

The preferable image forming layer of the present invention ischaracterized in that it contains a polymer compound having a functionalgroup that changes from one of hydrophilic to hydrophobic andhydrophobic to hydrophilic in the presence of an acid, by application ofheat, or by irradiation with radiation.

The essential component of the image forming layer of the presentinvention, a polymer compound having a polarity-changing group, isdescribed. The polarity-changing group to be introduced into the polymercompound includes two types as so mentioned above, that is, a functionalgroup that changes from hydrophobic to hydrophilic and a functionalgroup that changes from hydrophilic to hydrophobic.

B-1-1. Polymer Compound Comprising Functional Group that Changes fromHydrophobic to Hydrophilic in Side Chains:

Among the polymers having a polarity-changing group in the side chains,examples of the polymer having a functional group that changes fromhydrophobic to hydrophilic in the side chains include sulfonate polymersand sulfonamides described in JP-A No. 10-282672; and carboxylatepolymers described in EP Nos. 0652483, 6-502260 and 7-186562.

Of those polymers having side chains to change from hydrophobic tohydrophilic (polymer compounds including a functional group that changesfrom hydrophobic to hydrophilic), especially useful are secondarysulfonate polymers, tertiary carboxylate polymers, and alkoxyalkylcarboxylate polymers.

Examples of sulfonate polymers and carboxylate polymers usable in thepresent invention are mentioned below, however, the present invention isnot limited thereto. Compounds (1p-1) to (1p-8) are sulfonate polymers;and Compounds (a1) to (a10) are carboxylate polymers.

In case where the sulfonate polymer or the carboxylate polymer is usedin the present invention, those amount may be from 5 to 99% by weight,preferably from 10 to 98% by weight, and more preferably from 30 to 90%by weight based on the total solid content of the image forming layer(photosensitive or thermosensitive recording layer).

B-1-2. Polymer Compound Having Functional Group that Changes fromHydrophilic to Hydrophobic in Side Chains:

Examples of the polymer having a functional group in the side chainswherein the group changes from hydrophilic to hydrophobic (polymercompounds including a functional group that changes from hydrophilic tohydrophobic), include ammonium group-having polymers described in JP-ANo. 6-317899; and polymers having a decarboxylation typepolarity-changing group such as the following general formula (1), suchas sulfonylacetic acid, described in JP-A No. 2000-309174 (JapanesePatent Application No. 11-118295):

general formula (1)

wherein X represents —O—, —S—, —Se—, —NR³—, —CO—, —SO—, —SO₂—, —PO—,—SiR³R⁴—, or —CS; each of R¹, R², R³ and R⁴ independently represent amonovalent group; and M represents a cation.

Examples of R¹, R², R³ and R⁴ include —F, —Cl, —Br, —I, —CN, —R⁵, —OR⁵,—OCOR⁵, —OCOOR⁵, —OCONR⁵R⁶, —OSO₂R⁵, —COR⁵, —COOR⁵, —CONR⁵R⁶, —NR⁵R⁶,—NR⁵—COR⁶, —NR⁵—COOR⁶, —NR⁵—CONR⁶R⁷, —SR⁵, —SOR⁵, —SO₂R⁵, and —SO₃R⁵.

Examples of R⁵, R⁶ and R⁷ include a hydrogen atom, an alkyl group, anaryl group, an alkenyl group, and an alkynyl group. Specific examples ofthe functional groups can be referred to those mentioned above.

Preferably, each of R¹, R², R³ and R⁴ are a hydrogen atom, an alkylgroup, an aryl group, an alkynyl group, or an alkenyl group.

The polarity-converting polymer compound in the present invention may bea homopolymer of one monomer having a hydrophilic functional group asdescribed above, or a copolymer of two or more such monomers. Notinterfering with the effect of the present invention, it may be acopolymer with any other monomers.

Examples of the polymer compound having side chains that changes fromhydrophilic to hydrophobic used in the present invention are mentionedbelow (Compounds (P-1) to (P-17)). However, the present invention is notlimited thereto.

The amount of the polarity-changeable polymer compound to be used in theimage forming layer of the planographic printing plate precursor of thepresent invention is preferably from 0.01 to 94% by weight, morepreferably from 0.05 to 90% by weight of the total solid content of thelayer.

B-1-3. Other Components of the Present Invention:

The image forming layer of the planographic printing plate precursor ofthe present invention may contain, if desired, any other variouscompounds for getting various properties.

For example, the image forming layer of the planographic printing plateprecursor of the present invention may contain a dye having highabsorption in the visible light range, as an image colorant.

Concretely, examples of the dye includes Oil Yellow #101, Oil Yellow#103, Oil Pink #312, Oil Green BG, Oil Blue BOS, Oil Blue #603, OilBlack BY, Oil Black BS, Oil Black T-505 (all manufactured by OrientChemical Industry Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI 42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI 42000), Methylene Blue (CI 52015), as wellas the dyes described in JP-A No. 62-293247.

These dyes facilitate to show differentiation of the image area from thenon-image area in the image-formed plate, and it is desirable to add anyof them to the image forming layer. The amount of the dye in the imageforming layer is from 0.01 to 10% by weight of the total solid contentof the layer.

The image forming layer of the planographic printing plate precursor ofthe present invention may contain any of nonionic surfactants describedin JP-A Nos. 62-251740 and 3-208514, and ampholytic surfactantsdescribed in JP-A Nos. 59-121044 and 4-13149, for broadening thelatitude in stable processing of the precursor in various conditions fordevelopment.

Examples of the nonionic surfactants include sorbitan tristearate,sorbitan monopalmitate, sorbitan trioleate, stearic monoglyceride, andpolyoxyethylene nonylphenyl ether.

Examples of the ampholytic surfactants includealkyldi(aminoethyl)glycine, alkylpolyaminoethylglycine hydrochloride,2-alkyl-N-carboxyethyl-N -hydroxyethylimidazolium betaine, andN-tetradecyl-N,N-betaine (e.g., Amogen K, trade name, manufactured byDaiichi Kogyo Co., Ltd.). The amount of the nonionic surfactant or theampholytic surfactant used in the image forming layer of theplanographic printing plate precursor is preferably from 0.05 to 15% byweight, more preferably from 0.1 to 5% by weight of the layer.

Also if desired, the image forming layer of the planographic printingplate precursor of the present invention may contain a plasticizer formaking the layer flexible. Examples of the plasticizer includesbutylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate,dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresylphosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryloleate, and oligomers and polymers of acrylic acid or methacrylic acid.

Apart from these, the layer may contain any of onium salts,haloalkyl-substituted s-triazines, epoxy compounds, vinyl ethers, andalso hydroxymethyl-having phenol compounds and alkoxymethyl-havingphenol compounds described in Japanese Patent Application No. 7-18120.

In the present invention, the image forming layer may be formed bydissolving the above-mentioned components in a solvent and applying theresulting solution onto the hydrophilic layer. Examples of the solventusable herein includes ethylene dichloride, cyclohexanone, methyl ethylketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether,1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propylacetate, dimethoxyethane, methyl lactate, ethyl lactate,N,N-dimethylacetamide, N,N -dimethylformamide, tetramethylurea,N-methylpyrrolidone, dimethyl sulfoxide, sulforane, γ-butyrolactone,toluene and water. However, the present invention is not limitedthereto. One or more of these solvents may be used singly or incombination of two or more. The concentration of the constituentcomponents (total solid content including additives) in the solvent ispreferably from 1 to 50% by weight.

The dry weight (in terms of the solid content) of the image forminglayer may vary depending on the use thereof. In general, the dry weightthereof is from 0.1 g/m² to 10 g/m², preferably from 0.5 g/m² to 5 g/m².The sensitivity of the layer is higher when the coating amount thereofis lower. However, if the coating amount of the layer is too small, theprinting durability of the printing plate will be low. On the otherhand, the film properties of the layer are better when the coatingamount thereof is larger. However, if the coating amount of the layer istoo large, the sensitivity thereof will lower and the fine linereproduction in prints will be poor.

In order for forming the layer, various coating methods are employable.For example, employable are bar coating, spin coating, spraying, curtaincoating, dipping, air knife coating, blade coating and roll coating.

The image forming layer of the planographic printing plate precursor ofthe present invention may contain a surfactant having the ability toimprove the coatability of the layer. For example, the layer may containa fluorine-containing surfactant described in JP-A No. 62-170950.Preferably, the amount of the surfactant to be used in the image forminglayer is from 0.01 to 1% by weight, more preferably from 0.05 to 0.5% byweight of the total solid content of the layer.

Light to Heat Converting Substance:

In case where the planographic printing plate precursor of the presentinvention is treated through scanning exposure to IR laser light forforming image, it is desirable that the precursor contains somewheretherein a light to heat converting substance having the ability toconvert optical energy to heat energy. For example, the precursor maycontain a photo-thermal converting substance in any of the image forminglayer, the hydrophilic layer, and the surface layer of the substrate orthe substrate itself. Apart from these sites, the light to heatconverting substance may also be added to a thin layer that may beformed between the image forming layer and the crosslinked hydrophiliclayer, or between the substrate surface layer and the substrate.

The light to heat converting substance that may be used in theplanographic printing plate precursor of the present invention is notspecifically defined. The substance may be any one and selected fromevery substances capable of absorbing light such as UV light, visiblelight, IR light and white light to convert it into heat. Examplesthereof include carbon black, carbon graphite, pigment such asphthalocyanine pigment, iron powder, graphite powder, iron oxide powder,lead oxide, silver oxide, chromium oxide, iron sulfide, and chromiumsulfide. Especially preferable substances are dyes, pigments and metalscapable of effectively absorbing IR light falling between 760 nm and1200 nm.

The dyes may be any known ones, and examples thereof include thoseavailable as commercial products and those described in literature(e.g., in Dye Handbook, edited by the Organic Synthetic ChemistryAssociation of Japan, 1970). Concretely, examples thereof include azodyes, metal complexed azo dyes, pyrazolonazo dyes, anthraquinone dyes,phthalocyanine dyes, carbonium dyes, quinonimine dyes, methine dyes,cyanine dyes and metal thiolate complex dyes. Preferable examplesthereof include cyanine dyes described in JP-A Nos. 58-125246, 59-84356,59-202829 and 60-78787; methine dyes described in JP-A Nos. 58-173696,58-181690 and 58-194595; naphthoquinone dyes described in JP-A Nos.58-112793, 58-224793, 59-48187, 59-73996, 60-52940 and 60-63744;squalilium dyes described in JP-A No. 58-112792; and cyanine dyesdescribed in British Patent No. 434,875.

Examples of preferable dyes include near IR-absorbing sensitizersdescribed in U.S. Pat. No. 5,156,938; substitutedarylbenzo(thio)pyrylium salts described in U.S. Pat. No. 3,881,924;trimethinethiapyrylium salts described in JP-A No. 57-142645 (U.S. Pat.No. 4,327,169); pyrylium compounds described in JP-A Nos. 58-181051,58-220143, 59-41363, 59-84248, 59-84249, 59-146063 and 59-146061;cyanine dyes described in JP-A No. 59-216146; pentamethinethiopyryliumsalts described in U.S. Pat. No. 4,283,475; and pyrylium compoundsdescribed in JP-B Nos. 5-13514 and 5-19702. Still other examples ofpreferable dyes include near IR absorbent dyes of formulae (I) and (II)in U.S. Pat. No. 4,756,993. Of those dyes, especially preferable dyesare cyanine dyes, squarylium dyes, pyrylium salts and nickel-thiolatecomplexes.

Herein employable are commercial pigments and pigments disclosed inColor Index (C.I.) Handbook, Latest Pigment Handbook (edited by thePigment Technology Association of Japan, 1977), Latest PigmentApplication Technology (published by CMC, 1986) and Printing InkTechnology (published by CMC, 1984). Concrete examples of the pigmentsemployable herein include black pigments, yellow pigments, orangepigments, brown pigments, red pigments, purple pigments, blue pigments,green pigments, fluorescent pigments, metal powder pigments, andpolymer-bonded colorants. More concretely, examples thereof includeinsoluble azo pigments, azo-lake pigments, condensed azo pigments,chelate-azo pigments, phthalocyanine pigments, anthraquinone pigments,perylene and perinone pigments, thioindigo pigments, quinacridonepigments, dioxazine pigments, isoindolinone pigments, quinophthalonepigments, dyed lake pigments, azine pigments, nitroso pigments, nitropigments, natural pigments, fluorescent pigments, inorganic pigments,and carbon black. Of those pigments, preferable is carbon black.

These pigments may be surface-treated or not. As the surface-treatment,for example, the pigment particles may be coated with resin or wax; or asurfactant may be adhered to them; or a reactive substance (e.g., silanecoupling agent, epoxy compound, polyisocyanate) may be bonded to thesurfaces of the pigment particles. The surface treatment is described,for example, in Properties and Applications of Metal Soap (by MiyukiShobo), Printing Ink Technology (by CMC, 1984), and Latest PigmentApplication Technology (by CMC, 1986).

Preferably, the particle size of the pigment used in the presentinvention is from 0.01 μm to 10 μm, more preferably from 0.05 μm to 1μm, even more preferably from 0.1 μm to 1 μm. If the particle size ofthe pigment is smaller than 0.01 μm, it is unfavorable since the pigmentdispersion in the light to heat converting substance-containing layercoating liquid is not stable; but if larger than 10 μm, it is alsounfavorable since the light to heat converting substance-containinglayer may not be uniform. For dispersing the pigment, employable is anyknown dispersion technology for ink production or toner production. Thedispersing machine to be used may be any of an ultrasonic wavedispersing machine, sand mill, attritor, pearl mill, super mill, ballmill, impeller, disperser, KD mill, colloid mill, dynatron, three-rollmill, and pressure kneader. They are described in detail, for example,in Latest Pigment Application Technology (by CMC, 1986).

The amount of the dye or pigment to be used in the light to heatconverting substance-containing layer may be from 0.01 to 50% by weight,preferably from 0.1 to 10% by weight of the total solid content of thelayer. More preferably, the amount of the dye is from 0.5 to 10% byweight; and that of the pigment is from 3.1 to 10% by weight. If theamount of the pigment or dye is smaller than 0.01% by weight, the layerwill be ineffective for increasing the sensitivity of the precursor; butif larger than 50% by weight, the film strength of the light to heatconverting substance-containing layer will be low.

The planographic printing plate precursor produced in the manner may beexposed and developed in any known method in order to form aplanographic printing plate, and this plate is used in producing a largenumber of prints.

When thermal energy is applied to the image forming layer in theplanographic printing plate precursor of the present invention, theheated region of the layer changes from hydrophilic to hydrophobic, orfrom hydrophobic to hydrophilic. Depending on the type of change in thelayer, the exposed part or the non-exposed part of the image forminglayer changes into a hydrophobic ink-receiving image area or ahydrophilic non-image area of the layer. The image formation based onthe polarity change does not substantially require wet development.Therefore, after heat is applied to precursor or the precursor isexposed to light to form an image thereon, the precursor may be directlyset in a printer, not requiring any special wet development, and itreceives dampening water and ink in the printer, and serves as aprinting plate to produce prints.

Image formation may be carried out on the planographic printing plateprecursor of the present invention by applying heat to the precursor.When the precursor contains a light to heat converting substance asdescribed above, an image may be formed thereon through scanningexposure to IR laser light and the like.

Examples of method, which is employable for forming an image on theprecursor, include any method of thermal fixation, optical fixation,pressure fixation, and solvent fixation. Concretely, an image may beformed on the precursor through direct imagewise heating with a thermalrecording head, or through scanning exposure to IR laser light, orhigh-intensity flash exposure to a xenon discharge lamp, or exposure toan IR lamp.

In order for carrying out direct plate making using the precursor by acomputer-to-plate system having the ability to improve the productivity,it is desirable to fuse image portion thereof using laser. Examples ofthe laser include gas lasers such as carbon dioxide laser, nitrogenlaser, Ar laser, He/Ne laser, He/Cd laser, Kr laser; liquid (color)lasers; solid lasers such as ruby laser, Nd/YAG laser; semiconductorlasers such as GaAs/GaAlAs, InGaAs laser; and excimer lasers such as KrFlaser; XeCl laser, XeF laser, Ar₂. Above all, preferable laser isexposure to high-power type solid IR laser such as YAG laser or IRsemiconductor laser which emit 700-1200 nm light.

Thus the image forming layer of the precursor, which is exposedimagewise, has a hydrophilic region and a hydrophobic region formedtherein. In that condition, the precursor may be directly set in aprinter, in which it receives ink and dampening water in an ordinaryorder, and comes to serve as a printing plate to produce prints. Theplanographic printing plate precursor of the present invention may beset in a printer equipped with an exposing device, and it may be exposedto light to form an image thereon in the printer.

(B-2) Preferable Image Forming Layer of the Present Invention:

The image forming layer of the present invention may be characterized inthat it contains a hydrophobic precursor capable of forming ahydrophobic region through application of heat or to radiation such asthose of IR laser light.

First described component is the preferable component of the imageforming layer. The hydrophobic precursor may be particles that form ahydrophobic region in the image forming layer by application of heat.Examples thereof include thermoplastic polymer particles, thermosettingpolymer particles, thermo-reactive functional group-having polymerparticles, and microcapsules of a hydrophobic compound such as athermo-reactive functional group-having compound, which are dispersed inthe matrix of the hydrophilic image forming layer. The particles can bedispersed in a matrix of the image-forming layer. When applied heat, thepolymer particles of these compounds fuse or react with each other intoaggregates to form a hydrophobic region. In case of the microcapsules,the microcapsules include walls that are broken or become permeable byapplication of heat, so that the hydrophobic compound encapsulatedtherein is let out, whereby a predetermined region of the image-forminglayer changes polarity to become hydrophobic and form the hydrophobicregion.

The image forming layer may contain one or more different types of suchparticles or microcapsules.

B-2-1. Hydrophobic Precursor:

B-2-1-1. Thermoplastic Polymer Particles:

Examples of the thermoplastic polymer particles preferred for use in thepresent invention are described in, for example, Research Disclosure No.33303, January 1992, JP-A Nos. 9-123387, 9-131850, 9-171249 and9-171250, and EP No. 931647.

Examples of the polymer to form the polymer particles includeshomopolymers or copolymers of monomers such as ethylene, styrene, vinylchloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethylmethacrylate, vinylidene chloride, acrylonitrile, and vinylcarbazole,and their mixtures. Of those, more preferable polymers are polystyreneand polymethyl methacrylate.

Preferably, the mean particle size of the thermoplastic polymerparticles for use in the present invention is from 0.01 to 20 μm. Inorder to produce the polymer particles, any known method is employable.For example, they may be readily produced through ordinary emulsionpolymerization or suspension polymerization, but the method is notlimited thereto.

B-3-1-2. Thermosetting Polymer Particles:

Examples of the thermosetting polymer suitable for the thermosettingpolymer particles for use in the present invention includes resinshaving phenol-based structure, urea resins (e.g., those produced byresinifying urea or urea derivatives such as methoxymethylurea withaldehydes such as formaldehyde), melamine resins (e.g., those producedby resinifying melamine or its derivatives with aldehydes such asformaldehyde), alkyd resins, unsaturated polyester resins, polyurethaneresins, and epoxy resins.

Preferable examples of the resins having phenol-based structure includephenolic resins produced by resinifying phenol or cresol with aldehydessuch as formaldehyde, hydroxystyrene resins, methacrylamide oracrylamide resins having a phenol skeleton structure such as N-(p-hydroxyphenyl)methacrylamide, and methacrylate or acrylate resinshaving a phenol skeleton such as p-hydroxyphenyl methacrylate.

Of those, especially preferable are resins having phenol-basedstructure, melamine resins, urea resins and epoxy resins.

Preferably, the mean particle size of the thermosetting polymerparticles for use in the present invention is from 0.01 to 20 μm. Forproducing the polymer particles, for example, known is a method ofdissolving the polymer compound in a water-insoluble organic solvent,mixing it with an aqueous solution containing a dispersant, andsolidifying the resulting emulsion into fine particles by heating it toremove the organic solvent. Alternatively to it, thermosetting polymersmay be formed into fine particles while they are produced. However, thepresent invention is not limited to these methods.

B-2-1-3. Thermo-Reactive Functional Group Having Polymer Particles:

Examples of the thermo-reactive functional group in the thermo-reactivefunctional group-having polymer particles which are preferable for usein the present invention includes polymerizing ethylenically unsaturatedgroups (e.g., acryloyl group, methacryloyl group, vinyl group, allylgroup); isocyanate groups that can cause addition reaction, and theirblocked groups, and functional groups having active hydrogen atom whichare reaction partner groups of the isocyanate groups or blocked groups(e.g., amino group, hydroxyl group, carboxyl group); epoxy groups thatcan cause addition reaction, and their reaction partners, amino group,carboxyl group or hydroxyl group; carboxyl groups that can causecondensation with hydroxyl or amino group, and their reaction partners;acid anhydrides that can cause ring-opening addition reaction with aminoor hydroxyl group, and their reaction partners. However, any and everyfunctional group is acceptable herein so far as it forms some chemicalbond through chemical reaction.

Concrete examples of the thermo-reactive functional group in the polymerparticles for use in the image forming layer of the present inventionincludes an acryloyl group, a methacryloyl group, a vinyl group, anallyl group, an epoxy group, an amino group, a hydroxyl group, acarboxyl group, an isocyanate group, an acid anhydride group, and theirprotected groups. Introducing the functional group into the polymerparticles may be effected during polymerization of the polymer, or byproceeding polymer reaction for the group after polymerization of thepolymer.

In case where the thermo-reactive functional group is introduced intothe polymer for polymer particles during polymerization, it is desirablethat a thermo-reactive functional group-having monomer is prepared andthe monomer is polymerized into polymer by an emulsion polymerization orsuspension polymerization.

Examples of the thermo-reactive functional group-having monomer includeallyl methacrylate, allyl acrylate, vinyl methacrylate, vinyl acrylate,glycidyl methacrylate, glycidyl acrylate, 2-isocyanatoethyl methacrylateand its blocked isocyanates which is blocked with alcohol or the like,2-isocyanatoethyl acrylate and its blocked isocyanates which is blockedwith alcohol or the like, 2-aminoethyl methacrylate, 2-aminoethylacrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, acrylicacid, methacrylic acid, maleic anhydride, difunctional acrylates anddifunctional methacrylates. However, the thermo-reactive functionalgroup-having monomers usable in the present invention are not limitedthereto.

In producing the thermo-reactive functional group-having polymers, thethermo-reactive functional group-having monomers may be copolymerizedwith any other comonomers not having the thermo-reactive functionalgroup. Examples of the comonomers not having the functional groupinclude styrene, alkyl acrylates, alkyl methacrylates, acrylonitrile,and vinyl acetate, but these are not limited thereto. Any others nothaving such a thermo-reactive functional group may serve as thecomonomers.

The polymer reaction in order for introducing the thermo-reactivefunctional group into the polymers after polymerization is described,for example, in the pamphlet of International Patent PublicationLaid-Open No. 96/34316.

Preferably, the thermo-fusing temperature of the thermo-reactivefunctional group-having polymer particles is not lower than 70° C., morepreferably not lower than 100° C. in view of the storage stability ofthe polymer particles. However, if the thermo-fusing temperature of thepolymer particles is too high, it is unfavorable from the viewpoint ofthe sensitivity thereof. Therefore, the thermo-fusing temperature of thepolymer particles preferably is in a range of from 80 to 250° C., morepreferably 100 to 150° C.

Preferably, the mean particle size of the polymer particles is from 0.01to 20 μm, more preferably 0.05 to 2.0 μm, most preferably 0.1 to 1.0 μm.Within the range, the polymer particles ensure good image resolution andstorage stability of the image forming layer containing them.

B-2-1-4. Microcapsules of Hydrophobic Compound:

Next described are the microcapsules wherein a hydrophobic substance isencapsulated therein. The hydrophobic substance is preferably a compoundhaving a thermo-reactive functional group.

As the thermo-reactive functional group in the hydrophobic compound tobe encapsulated into microcapsules, those mentioned above for thethermo-reactive functional group-having polymer particles are preferablyusable and referred to. Concrete examples of the group includespolymerizing unsaturated groups (polymerizable ethylenically unsaturatedgroups), hydroxyl groups, carboxyl groups, carboxylate groups, acidanhydride groups, amino groups, epoxy groups, isocyanate groups, andblocked isocyanate groups.

The compounds having polymerable unsaturated group are preferablycompounds having at least one, more preferably at least two,ethylenically unsaturated bonds such as acryloyl group, methacryloylgroup, vinyl group and allyl group. These compounds are well known inthe industrial field. Without specific limitation thereon, any and everycompound of these type is employable in the present invention. As itschemical form, the compound includes monomers, prepolymers, e.g.,dimers, trimers and oligomers, and their mixtures and copolymers.

Concrete examples of the compound includes unsaturated carboxylic acids(e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid,isocrotonic acid, maleic acid), esters thereof, and unsaturatedcarboxamides. Above all, preferable compounds for use herein are estersobtained by a reaction of unsaturated carboxylic acids with aliphaticpolyalcohols, and amides obtained by a reaction of unsaturatedcarboxylic acids with aliphatic polyamines.

Also preferable are adducts obtained by a reaction of unsaturatedcarboxylates or unsaturated carboxamides having a nucleophilicsubstituent such as hydroxyl, amino or mercapto group, withmonofunctional or polyfunctional isocyanates or epoxides; and dehydratedpolycondensates obtained by a reaction of such unsaturated carboxylatesor carboxamides with monofunctional or polyfunctional carboxylic acids.

Also preferable for use herein are adducts obtained by a reaction ofunsaturated carboxylates or amides having an electrophilic substituentsuch as isocyanate or epoxy group with monofunctional or polyfunctionalalcohols, amines or thiols; and substitution products obtained by areaction of unsaturated carboxylates or amides having a eliminatablesubstituent such as halogen or tosyloxy group, with monofunctional orpolyfunctional alcohols, amines or thiols.

Still other examples also preferable for use in the present inventioninclude compounds corresponding to those mentioned above in which,however, the unsaturated carboxylic acids or unsaturated carboxylic acidportion are replaced with unsaturated phosphonic acids orchloromethylstyrenes.

Examples of the esters obtained from unsaturated carboxylic acids andaliphatic polyalcohols are shown below.

Examples of acrylates include ethylene glycol diacrylate, triethyleneglycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycoldiacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate,trimethylolpropane diacrylate, trimethylolpropane triacrylate,trimethylolpropane tris(acryloyloxypropyl)ether, trimethylolethanetriacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate,tetraethylene glycol diacrylate, pentaerythritol diacrylate,pentaerythritol triacrylate, pentaerythritol tetraacrylate,dipentaerythritol diacrylate, dipentaerythritol pentaacrylate,dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitoltetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate,tris(acryloyloxyethyl)isocyanurate, and polyester acrylate oligomers.

Examples of methacrylates include tetramethylene glycol dimethacrylate,triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate,trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate,ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate,hexanediol dimethacrylate, pentaerythritol dimethacrylate,pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate,dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate,sorbitol trimethacrylate, sorbitol tetramethacrylate,bis[p-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]-dimethylmethane, andbis-[p -(methacryloyloxyethoxy)phenyl]dimethylmethane.

Examples of itaconates include ethylene glycol diitaconate, propyleneglycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanedioldiitaconate, tetramethylene glycol diitaconate, pentaerythritoldiitaconate, and sorbitol tetraitaconate.

Examples of crotonates include ethylene glycol dicrotonate,tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, andsorbitol tetra/dicrotonate.

Examples of isocrotonates include ethylene glycol diisocrotonate,pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.

Examples of maleates include ethylene glycol dimaleate, triethyleneglycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

Examples of other esters also usable herein include aliphatic alcoholesters described in JP-B Nos. 46-27926, 51-47334, 57-196231; aromaticskeleton-having esters described in JP-A Nos. 59-5240, 59-5241,2-226149; and amino group-having esters described in JP-A No. 1-165613.

Examples of the amide monomers obtained from aliphatic polyaminecompounds and unsaturated carboxylic acids includemethylenebis-acrylamide, methylenebis-methacrylamide,1,6-hexamethylenebis-acrylamide, 1,6-hexamethylenebis -methacrylamide,diethylenetriamine-trisacrylamide, xylylenebisacrylamide, andxylylenebismethacrylamide.

Other amide monomers also preferable for use herein are those having acyclohexylene structure described in, for example, JP-B No. 54-21726.

Urethane-based polyadducts produced through addition reaction ofisocyanates with a hydroxyl group are also preferable for use in thepresent invention. Concrete examples thereof include urethane compoundshaving at least two polymerizable unsaturated groups in a molecule,which are obtained by adding a hydroxyl group-having unsaturated monomerof the following formula (III) to a polyisocyanate compound having atleast two isocyanate groups in one molecule. These are described in JP-BNo. 48-41708.CH₂═C(R¹) COOCH₂CH(R²)OH  (III)wherein R¹ and R² each represent H or CH₃.

Also preferable for use in the present invention are urethane acrylatesdescribed in JP-A No. 51-37193, and JP-B Nos. 2-32293 and 2-16765; andethylene oxide-based urethane compounds described in JP-B Nos. 58-49860,56-17654, 62-39417 and 62-39418.

Also preferable are radical-polymerizable compounds having an aminostructure or a sulfide structure in the molecule, described in JP-A Nos.63-277653, 63-260909 and 1-105238.

Other examples which is preferable for use in the present inventioninclude polyfunctional acrylates and methacrylates, such as polyesteracrylates and epoxy acrylates obtained through reaction of epoxy resinswith (meth)acrylic acid, described in JP-A No. 48-64183, and JP-B Nos.49-43191 and 52-30490. Also preferable are specific unsaturatedcompounds described in JP-B Nos. 46-43946, 1-40337 and 1-40336; andvinylphosphonic acid compounds described in JP-A No. 2-25493. As thecase may be, perfluoroalkyl group-having compounds described in JP-A No.61-22048 are also preferable. Further, photocurable monomers andoligomers described in the Journal of the Adhesive Association of Japan,Vol. 20, No. 7, pp. 300-308 (1984) are also preferable.

Examples of preferable epoxy compounds include glycerin polyglycidylether, polyethylene glycol diglycidyl ether, polypropylene diglycidylether, trimethylolpropane polyglycidyl ether, sorbitol polyglycidylether, and polyglycidyl ethers of bisphenols or polyphenols orhydrogenated compounds thereof.

Preferable examples of isocyanate compounds include tolylenediisocyanate, diphenylmethane diisocyanate, polymethylene-polyphenylpolyisocyanate, xylylene diisocyanate, naphthalene diisocyanate,cyclohexanephenylene diisocyanate, isophorone diisocyanate,hexamethylene diisocyanate, cyclohexyl diisocyanate, and theirderivatives blocked with alcohols or amines.

Examples of preferable amine compounds include ethylenediamine,diethylenetriamine, triethylenetetramine, hexamethylenediamine,propylenediamine, and polyethylenimine.

Examples of preferable hydroxyl group-containing compounds includecompounds terminated with methylol group, polyalcohols such aspentaerythritol, bisphenols and polyphenols.

Examples of preferable carboxyl group-containing compounds includearomatic polycarboxylic acids such as pyromellitic acid, trimelliticacid, phthalic acid; and aliphatic polycarboxylic acids such as adipicacid.

Examples of preferable acid anhydrides include pyromellitic anhydride,and benzophenonetetracarboxylic anhydride.

Examples of preferable copolymers of ethylenic unsaturated compoundsinclude allyl methacrylate copolymers. Concrete examples thereof includeallyl methacrylate/methacrylic acid copolymers, allyl methacrylate/ethylmethacrylate copolymers, and allyl methacrylate/butyl methacrylatecopolymers.

For forming microcapsules, any known method is employable. Examplesthereof include a method of coacervation described in U.S. Pat. Nos.2,800,457 and 2,800,458; a method of interfacial polymerizationdescribed in British Patent No. 990,443, U.S. Pat. No. 3,287,154, JP-BNos. 38-19574, 42-446, 42-711; a method of polymer precipitationdescribed in U.S. Pat. Nos. 3,418,250 and 3,660,304; a method of usingan isocyanate-polyol wall-forming material described in U.S. Pat. No.3,796,669; a method of using an isocyanate wall-forming materialdescribed in U.S. Pat. No. 3,914,511; a method of using anurea-formaldehyde or urea-formaldehyde-resorcinol wall-forming materialdescribed in U.S. Pat. Nos. 4,001,140, 4,087,376 and 4,089,802; a methodof using a melamine-formaldehyde resin or hydroxy cellulose as awall-forming material described in U.S. Pat. No. 4,025,445; a method ofin-situ polymerization of monomers described in JP-B Nos. 36-9163 and51-9079; a spray-drying method described in British Patent No. 930,422and U.S. Pat. No. 3,111,407; and an electrolytic dispersion coolingmethod described in British Patent Nos. 952,807 and 967,074. However,the present invention is not limited to these methods.

The microcapsule walls which are preferable for the microcapsules foruse in the present invention have a three-dimensional crosslinkedstructure, and they can swell in solvents. From this viewpoint, it isdesirable that the wall material for the microcapsule is polyurea,polyurethane, polyester, polycarbonate, polyamide or their mixture.Especially preferable materials are polyurea and polyurethane. Ifdesired, a compound having thermo-reactive functional group such asthose described above may be introduced into the microcapsule walls.

Preferably, the mean particle size of the microcapsules is from 0.01 to20 μm, more preferably 0.05 to 2.0 μm, most preferably 0.10 to 1.0 μm.Within the range, the microcapsules can provide good image resolutionand storage stability of the image forming layer containing them.

In the image forming mechanism wherein microcapsules of a hydrophobicsubstance (thermo-reactive functional group-having compound) are used,any compound of the microcapsule material, the compound contained in themicrocapsules and other optional components, which exist in thethermo-sensitive layer that contains the microcapsules dispersedtherein, can react with each other to form an image region which is ahydrophobic region (ink-acceptable region). Various embodiments willsatisfy the requirement. Examples of the mechanism include one typemechanism wherein the microcapsules fuse each other when heat is appliedas described above; another type mechanism wherein the encapsulatedcompound have oozed on the outer surfaces of the microcapsules orcompletely oozed through the microcapsules in a coating step of applyinga microcapsule dispersion onto a substrate, or an outer compound havepenetrated into the microcapsules in a coating step, and chemicalreaction is caused under heat due to the oozed compound or penetratedcompound; and still another type mechanism wherein the microcapsulematerial and/or the encapsulated compound reacts with a hydrophilicresin or a low-molecular compound which is added to the layer; and stillanother type mechanism wherein at least two different types ofmicrocapsule wall materials or at least two different types compounds tobe encapsulated are prepared such that they have different functionalgroups capable of undergoing thermal reaction with each other, and usedin combination so that the microcapsules can react with each other. Thepresent invention can employ any of such types of image formation.

Accordingly, the thermal fusion of microcapsules is one preferableembodiment for image formation but is not indispensable in the presentinvention.

Preferably, the amount of the hydrophobic precursor, which is selectedfrom the thermoplastic polymer particles, thermosetting polymerparticles, thermo-reactive functional group-having polymer particles,microcapsules and the like to be added to the image forming layer isfrom 20 to 99% by weight of the solid content of the layer, and morepreferably 40 to 90% by weight. Within the range, the image forminglayer can achieve good in-printer development, good image formation,high sensitivity and good printing durability.

B-2-2. Hydrophilic Resin:

In the present invention, the image forming layer can contain ahydrophilic resin in order for providing better in-printerdevelopability and higher film strength of the heat-sensitive layer.

From the viewpoint of the in-printer developability of the image forminglayer, it is desirable that the hydrophilic resin is notthree-dimensionally crosslinked. Desirable concrete examples includehydrophilic resin having a hydrophilic group such as hydroxyl, carboxyl,hydroxyethyl, hydroxypropyl, amino, aminoethyl, aminopropyl andcarboxymethyl groups.

Examples of the hydrophilic resin include gum arabic, casein, gelatin,starch derivatives, carboxymethyl cellulose and its salts, celluloseacetate, sodium alginate, vinyl acetate-maleic acid copolymers,styrene-maleic acid copolymers, polyacrylic acids and their salts,polymethacrylic acid and their salts, homopolymers and copolymers ofhydroxyethyl methacrylate, homopolymers and copolymers of hydroxyethylacrylate, homopolymers and copolymers of hydroxypropyl methacrylate,homopolymers and copolymers of hydroxypropyl acrylate, homopolymers andcopolymers of hydroxybutyl methacrylate, homopolymers and copolymers ofhydroxybutyl acrylate, polyethylene glycols, hydroxypropylene polymers,polyvinyl alcohols, hydrolyzed polyvinyl acetates having a degree ofhydrolysis of at least 60% by weight, and preferably at least 80% byweight, polyvinylformals, polyvinylbutyrals, polyvinylpyrrolidones,homopolymers and copolymers of acrylamide, homopolymers and copolymersof methacrylamide, homopolymers and copolymers of N-methylolacrylamide,2-acrylamido-2-methylpropane sulfonic acid and its salts.

The amount of the hydrophilic resin to be in the image forming layer ispreferably from 2 to 40% by weight, more preferably from 3 to 30% byweight of the solid content of the layer. Within the range, the imageforming layer ensures good in-printer developability and high filmstrength.

B-2-3. Light to Heat Converting Agent:

In case where the planographic printing plate precursor of the presentinvention is processed through scanning exposure to laser light forforming image thereon, it is desirable that at least one layer comprisedin the precursor contains a light to heat converting agent having theability to convert optical energy to heat energy.

The light to heat converting agent that may be comprised in theplanographic printing plate precursor of the present invention can beselected from every substances capable of absorbing light which is notshorter than 700 nm to convert light into heat. The light to heatconverting agent is not specifically defined, and therefore, variouspigments and dyes are usable for the light to heat converting agent.Especially preferable substances are dyes, pigments, metal powders andmetal compound powders capable of effectively absorbing IR light in arange of from 760 nm to 1200 nm.

As the pigments usable and preferable for the light to heat convertingagent in this embodiment, those mentioned above can be usable andreferred to.

In case where the pigment is added to the image forming layer in thepresent invention, it is desirable that the pigment particles are coatedwith a hydrophilic resin or silica sol since the particles coated by theresin are uniformly dispersed in the water-soluble or hydrophilic resinwhich is a matrix of the image forming layer, and do not interfere thehydrophilicity of the matrix. In particular, carbon black particlestreated with such a coating are very useful, as they are suitable forexposure to IR-emitting laser.

Preferably, the particle size of the pigment particles is from 0.01 to 1μm, and more preferably 0.01 to 0.5 μm. As dispersing the pigment in thedesired layer, any known dispersion technique generally used in inkproduction or toner production is employable. As the dispersing machineto be used for the purpose, those mentioned above are usable andreferred to.

The dyes usable as the light to heat converting agent in the presentinvention may be commercial dyes and other known dyes described inliterature (e.g., Dye Handbook (edited by the Association of OrganicSynthetic Chemistry of Japan, 1970); Chemical Industry, May 1986, pp.45-51, “Near-IR Absorbing Dyes”; Development and Market Trend ofFunctional Dyes in 1990s, Chap. 2, Sec. 2.3 (by CMC, 1990)) or in patentspecifications.

Concretely, as the dyes usable and preferable herein, those mentionedabove are usable and referred to. In addition, also usable dye are thedyes described in U.S. Pat. No. 4,756,993; cyanine dyes described inU.S. Pat. No. 4,973,572; the dyes described in JP-A No. 10-268512; andphthalocyanine compounds described in JP-A 11-235883.

Preferable commercial products to be used as the dye are EPOLITEIII-178, EPOLITE III-130 and EPOLITE III-125 manufactured by Epolin,Ltd.

Above all, dyes having a water-soluble functional group are especiallypreferable as a dye added to the hydrophilic image forming layer. Someexamples of the dyes are mentioned below, however, the present inventionis not limited thereto.

When dye and/or pigment is used as the light to heat converting agent,the amount of the dye or pigment added to the thermo-sensitive layer isat most 30% by weight, preferably from 3 to 25% by weight and morepreferably from 4 to 20% by weight of the total solid content of thelayer. Within the range, the layer has good sensitivity.

The thermo-sensitive layer of the present invention may contain metalparticles as a light to heat converting agent. Most metal particles havethe capability of light to heat conversion, and are self-exothermicmaterial. Preferable metal particles for use herein are particles ofsimple metals or alloys of, for example, Si, Al, Ti, V, Cr, Mn, Fe, Co,Ni, Cu, Zn, Y, Zr, Mo, Ag, Au, Pt, Pd, Rh, In, Sn, W, Te, Pb, Ge, Re,Sb, or their oxides or sulfides.

Among the metals to form the metal powders, especially preferable metalsare those capable of thermally fusing into aggregates when it is exposedto light, those having a melting point of about 1000° C. or lower andthose capable of absorbing visible light, UV light or IR light. Examplesthereof include Re, Sb, Te, Au, Ag, Cu, Ge, Pb and Sn.

More preferable examples are those having a relatively low melting pointand having a relatively high IR absorbance such as metal powders of Ag,Au, Cu, Sb, Ge and Pb; and most preferable are Ag, Au and Cu.

Two or more different types of light to heat converting substances maybe combined used for the present invention. For example, mixtures oflow-melting-point metal particles such as those of Re, Sb, Te, Au, Ag,Cu, Ge, Pb and Sn, and self-exothermic metal particles such as those ofTi, Cr, Fe, Co, Ni, W and Ge may be used. Also preferable is combinationof particles having an especially high-level light absorption such asthose of Ag, Pt or Pd and metal particles of any other metal.

In case where the metal (compound) particles described above are used asthe light to heat converting agent, it is desirable that the surfaces ofthe metal particles are hydrophilicated, since the hydrophilicated metalparticles are more effective.

In order to provide hydrophilicity to their surfaces, for example, theparticles can be surface-treated with a hydrophilic compound, which canbe adsorbed by the particles, such as a surfactant; or the particles canbe surface-treated with a substance having a hydrophilic group which canreact with the constituents of the particles; or the particles can becoated with a hydrophilic polymer film of protective colloid.Preferably, the surfaces of the metal particles are treated with asilicate. For example, the surface of iron particles can be fullyhydrophilicated by a method of dipping the particles in a 31 aqueoussolution of sodium silicate at 70° C. for 30 seconds. Other metalparticles can be also subjected in the same manner.

Preferably, the size of the metal particles that are used as a light toheat converting agent is at most 10 μm, more preferably 0.003 to 5 μm,and most preferably 0.01 to 3 μm. Within the range, the particles ensuregood sensitivity and good image resolution.

In case where such metal particles are used as the light to heatconverting agent herein, the amount of the particles to be added to theimage forming layer is at least 5% by weight, and preferably from 10 to50% by weight of the solid content of the layer. Within the range, thelayer can have high sensitivity.

The light to heat converting agent can be comprised in any other layerinstead of within the image forming layer. For example, the light toheat converting agent can be comprised in the undercoat layer just belowthe image forming layer, or in a water-soluble overcoat layer that willbe described hereinafter. When at least one of the image forming layer,the undercoat layer or the overcoat layer contains the light to heatconverting agent, the IR absorption efficiency of the printing plateprecursor increases and the sensitivity thereof increases.

B-2-1-4. Other Components:

If desired, any other and various compounds may be added to the imageforming layer of the planographic printing plate precursor of thepresent invention, in order that the layer may have various properties.

Inorganic Particles:

Inorganic particles may be added to the image forming layer of thepresent invention. Preferable examples of the inorganic particlesinclude silica, alumina, magnesium oxide, titanium oxide, magnesiumcarbonate, calcium alginate and their mixtures. Even if they do notserve as a light to heat converting agent, these inorganic particles areeffective for reinforcing the film and for roughening the surface of thefilm to improve an interfacial adhesive property of the film.

Preferably, the particle size of the inorganic particles is 5 nm to 10μm, and more preferably 10 nm to 1 μm. Within the range, the inorganicparticles can stably disperse in hydrophilic resin along with otherresin particles and metal particles serving as a light to heatconverting agent, and the image forming layer can have sufficient filmstrength and, as a result, a non-image area having high hydrophilicityresistant with respect to printing stains can be formed.

These inorganic particles are easily available on the market ascommercial products such as colloidal silica dispersions. The amount ofthe inorganic particles to be comprised in the image forming layer ispreferably from 1.0 to 70% by weight, and more preferably from 5.0 to50% by weight of the total solid content of the layer.

Colorant and Plasticizer:

The image forming layer of the planographic printing plate precursor ofthe present invention may contain a colorant and a plasticizer, likethat mentioned above. Those mentioned above as preferable examples arealso usable and referred to.

Solvent:

In case where microcapsules are added to the image forming layer, asolvent capable of dissolving the compound encapsulated in themicrocapsules and capable of swelling the capsule wall material may beadded to the dispersant of the microcapsules. The solvent promotes thediffusion of the encapsulated, thermo-reactive functional group-havinghydrophobic compound, out of the microcapsules.

Selection of the solvent depends on the dispersing medium for themicrocapsules, the wall material for the microcapsules, the wallthickness and the contents of the microcapsules, and the solvent may bereadily selected from many commercial products. For example, forwater-dispersible microcapsules wherein the walls are made ofcrosslinked polyurea or polyurethane, the solvent is preferably selectedfrom alcohols, ethers, acetals, esters, ketones, polyalcohols, amides,amines and fatty acids.

Concrete examples of the solvent includes methanol, ethanol,tert-butanol, n-propanol, tetrahydrofuran, methyl lactate, ethyllactate, methyl ethyl ketone, propylene glycol monomethyl ether,ethylene glycol diethyl ether, ethylene glycol monomethyl ether,γ-butyrolactone, N,N-dimethylformamide and N,N-dimethylacetamide.However, the present invention is not limited thereto. If desired, twoor more of solvents may be combined in order for using herein.

A solvent which can not be dissolved in the microcapsule dispersion byitself, but can dissolved therein when the solvent is combined withother solvent mentioned above may also be used. The amount of thesolvent is determined, depending on a combination of other materials.However, if the amount of the solvent is lower than a proper amount, theimage formation can not be carried out satisfactory; but if too large,the dispersion is unstable. In general, the amount of the solvent ispreferably from 5 to 95% by weight, more preferably 10 to 90% by weight,and even more preferably from 15 to 85% by weight of the coating liquidfor the image-recording layer.

Reaction Initiator, Reaction Promoter:

In case where microcapsules of a thermo-reactive functional group-havingcompound or polymer particles having thermo-reactive functional groupare used in the image forming layer of the present invention, a compoundhaving the ability to initiate or promote the reaction of thethermo-reactive functional group-having compound may be added to thelayer, if desired. Examples of the compound which can initiate orpromote the reaction comprise a compound that generates a radical orcation when exposed to heat. Concrete examples thereof include lophinedimers, trihalomethyl compounds, peroxides, azo compounds, onium saltssuch as diazonium salts or diphenyliodonium salts, acylphosphines andimidosulfonates.

Preferably, the amount of the compound to be added to the image forminglayer is from 1 to 20% by weight, and more preferably 3 to 10% by weightof the solid content of the layer. Within the range, the compound can beeffective for initiating or promoting the reaction, and do notdetracting from the in-printer developability of the printing plateprecursor.

Formation of Image forming Layer Used in the Present Invention:

In the present invention, the image forming layer can be formed bydissolving or dispersing the necessary components as above in water orin a mixed solvent optionally containing an organic solvent to prepare acoating liquid, followed by applying the coating liquid onto asubstrate. The solid content concentration of the coating liquid forforming the image forming layer is preferably from 1 to 50%.

If desired, a surfactant may be added to the coating liquid for theimage forming layer for improving the coatability of the liquid and forimproving the properties of the coating film. As the surfactant and itspreferable examples, those mentioned above are also usable and referredto. As the coating method and examples thereof, also referred to andusable are mentioned above.

The amount (solid content) of the image forming layer formed on thesubstrate after coating and drying in that manner varies depending onthe use of the printing plate produced. Generally, however, the amountis preferably 0.5 to 5.0 g/m², and more preferably from 0.5 to 2.0 g/m².

(C) Compound that is Capable of Forming Hydrophobic Surface Regionthrough Exposure to Heat or Radiation of the Present Invention:

The compound having the function of image formation, which may be addedto any of the hydrophilic layer of the present invention, is a compoundforms a hydrophobic surface region by application of heat, or byirradiation with radiation. The compound may be comprised in thehydrophilic layer. Examples thereof includes a compound wherein theproperty thereof can change from hydrophilic to hydrophobic byapplication of heat, or by irradiation with radiation, andthermo-fuseable hydrophobic particles.

C-1. Compound that is Changing from Hydrophilic to Hydrophobic:

One example of the compound that changes from hydrophilic to hydrophobicis a polymer having a functional group capable of being decarboxylatedthrough application of heat to change from hydrophilic to hydrophobic,described in JP-A No. 2000-122272 (Japanese Patent Application No.10-229783). Preferable examples of the polymer are mentioned below.Regarding the physical properties of the polymer of the type, it isdesirable that, when the polymer is formed into a film, the contactangle between the polymer film surface and a water drop in air (aairborne water drop) is at most 20° before the film is heated, butincreases to at least 65° after the film has been heated. However, thepresent invention is not limited to it.

Examples of the polymer having a functional group capable of changingfrom hydrophilic to hydrophilic in the side chains (in the presentinvention, the description of “in the side chains” may contains ameaning of “as the side chain”) include those of the polymer compoundhaving, in the side chains, a functional group capable of changing fromhydrophilic to hydrophilic, described above in B-2 in the section of thepresent invention. As the preferable examples of the polymer of the typeemployable herein, those mentioned in B-2 are also preferable.

C-2. Thermo-Fuseable Hydrophobic Particles:

Examples of the thermo-fuseable hydrophobic particles usable in thepresent invention include polystyrene particles described in EP No.816070. In addition, microcapsules of hydrophobic particles described inWO94/23954 are also usable herein for the same purpose.

The thermo-fuseable hydrophobic particles that can serve as an imageforming component in the hydrophilic layer of the present invention fuseand bond to each other, when heated or when exposed to IR laser lightand heated due to the exposure, and they form a hydrophobic region(ink-receiving region, image region). The particles are those of ahydrophobic organic compound.

In order that the particles rapidly fuse when they are appliedpredetermined heat, it is desirable that the hydrophobic organiccompound has a melting point (thermo-fuseable temperature) of from 50 to200° C. If the thermo-fusing temperature of the thermo-fuseablehydrophobic particles is lower than 50° C., it is unfavorable since theparticles may soften or fuse owing to the influence of heat providedthereto while the coating film is dried in the process of producing theplate precursor or owing to the influence of the ambient temperaturethereon during storage. Preferably, the thermo-fusing temperature of theparticles is not lower than 80° C., more preferably not lower than 100°C. in consideration of the storage stability of the precursor. Theparticles having a higher melting point are more stable. However, fromthe viewpoint of the recording sensitivity and the handlability of theprecursor, the melting point of the particles is preferably not higherthan 200° C.

Concrete examples of the hydrophobic organic compound to form thethermo-fuseable hydrophobic particles includes resins such aspolystyrene, polyvinyl chloride, polymethyl methacrylate, polyvinylidenechloride, polyacrylonitrile, polyvinyl carbazole, and their copolymersor mixtures. Also preferable examples thereof include paraffin wax,microcrystalline wax; polyolefin wax such as polyethylene wax andpolypropylene wax; fatty acid wax such as stearamide, linolenamide,laurylamide, myristylamide, palmitamide and oleamide; and higher fattyacids such as stearic acid, tridecanoic acid and palmitic acid.

Among thermo-fuseable hydrophobic particles as the image formingcomponents to be in the hydrophilic layer of the present invention,preferable component is thermo-fuseable hydrophobic particles of thehydrophobic organic compound mentioned above, which can readily fuse andaggregate when heated, in view of their ability of image formation. Inparticular, more preferable particles are those having hydrophilicsurfaces and capable of readily dispersing in water since they do notlower the hydrophilicity of the layer containing them.

Regarding the hydrophilicity of the surfaces of the thermo-fuseablehydrophobic particles, it is desirable that, when liquid containing thethermo-fuseable hydrophobic particles alone are applied onto a substrateand dried at a temperature lower than the solidifying temperature of theparticles, the contact angle of the thus-formed film (to a water drop inair) is smaller than the contact angle of a film of the particles (to awater drop in air) wherein a drying temperature thereof is higher thanthe solidifying temperature of the particles. In order that the surfacehydrophilicity of the thermo-fuseable hydrophobic particles satisfiesthe preferable condition, a hydrophilic polymer or oligomer such asthose of polyvinyl alcohol or polyethylene glycol, or a hydrophiliclow-molecular compound can be adsorbed in the surfaces of thethermo-fuseable hydrophobic particles. However, the method ofhydrophilicating the surfaces of the thermo-fuseable hydrophobicparticles is not limited thereto, and any known surface-hydrophilicatingmethods are employable for the purpose.

Preferably, the mean particle size of the thermo-fuseable hydrophobicparticles is from 0.01 to 20 μm, more preferably 0.05 to 2.0 μm, mostpreferably 0.1 to 1.0 μm. If their mean particle size is too large, theresolution of the precursor will be lower; but if too small, the storagestability of the precursor will be low.

The amount of the thermo-fuseable hydrophobic particles to be used inthe hydrophilic layer is preferably from 30 to 98% by weight, morepreferably 40 to 95% by weight of the solid content of the layer.

In the planographic printing plate precursor of the present invention,the hydrophilic layer having the function of image formation maycontain, if desired, any other various compounds for getting variousproperties.

Light to Heat Converting Substance:

In case where the planographic printing plate precursor of the presentinvention is processed through scanning exposure to laser light forforming image thereon, it is desirable that the precursor containssomewhere therein a light to heat converting substance having theability to convert optical energy to heat energy. The details of thelight to heat converting substance are the same as those mentionedabove. The precursor may contain a light to heat converting substance inany position such as the hydrophilic image forming layer, the surfacelayer of the substrate or the substrate itself. Apart from these sites,the light to heat converting substance may also be added to a thin layerthat may be formed between the substrate surface layer and thesubstrate.

Thus produced, the planographic printing plate precursor of the presentinvention may be exposed and developed in any known manner into aplanographic printing plate, and this is used in producing a largenumber of prints.

Regarding the mechanism of image formation on the planographic printingplate precursor of the present invention, a compound such asthermo-fuseable hydrophobic particles which are capable of forming ahydrophobic surface region fuses to each other in the region of thehydrophilic layer wherein heat is applied or radiation is irradiated toform a hydrophobic region which is an ink-receiving image region. On theother hand, in the region of the hydrophilic layer wherein heat is notapplied or radiation is not irradiated, the hydrophilic layer remains asit is, and forms a non-image region of high hydrophilicity. Therefore,the printing plate precursor of this embodiment realizes superiorin-printer developability, and thereby merely requiring simple treatmentwith water or not requiring any specific wet development at all, and itcan be directly set in a printer and processed into a printing plate.

Regarding the process of image formation on the planographic printingplate precursor of the present invention, the methods and the conditionsmentioned hereinabove can be also used.

In the present invention, due to imagewise-exposure, the hydrophiliclayer of the precursor can have a hydrophobic region converted by heatand a hydrophilic region still having the original hydrophilicity. Inthat condition, the precursor can be directly set in a printer, in whichthe precursor receives ink and dampening water in an ordinary order, andcomes to serve as a printing plate to produce prints. The planographicprinting plate precursor of the present invention can be set in aprinter equipped with an exposing device, and it can be exposed to lightto form an image portion thereof in the printer.

Overcoat Layer:

In the present invention, a hydrophilic overcoat layer may be formed onthe image forming layer of the planographic printing plate precursor forprotecting the hydrophilic surface of the image forming layer from beingcontaminated with oleophilic substances while the precursor is storedand for protecting it from being contaminated with fingerprints whilethe precursor is handled by hand.

The hydrophilic overcoat layer can be readily removed while theprecursor is processed in printers, and the layer contains a resinselected from water-soluble resins and water-swellable resins which ispartially crosslinked the water-soluble resins.

Examples of the water-soluble resins include water-soluble naturalpolymers and water-soluble synthetic polymers. They have an ability toform a film when applied onto the image forming layer and dried thereon,and are used alone or along with a crosslinking agent.

Examples of the water-soluble resins which are preferable for use in thepresent invention include natural polymers such as gum arabic,water-soluble soybean polysaccharides, cellulose derivatives (e.g.,carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose) andtheir modified derivatives, white dextrin, pullulan, enzymolysisetherified dextrin; and synthetic polymers such as polyvinyl alcohols(prepared by hydrolyzing polyvinyl acetates to a degree of at least65%), polyacrylic acids and their alkali metal salts and amine salts,polyacrylic acid copolymers and their alkali metal salts and aminesalts, polymethacrylic acids and their alkali metal salts and aminesalts, vinyl alcohol/acrylic acid copolymers and their alkali metalsalts and amine salts, polyacrylamides and their copolymers,polyhydroxyethyl acrylates, polyvinyl pyrrolidones and their copolymers,polyvinyl methyl ethers, vinyl methyl ether/maleic anhydride copolymers,poly-2-acrylamido-2-methyl-1-propanesulfonic acids and their alkalimetal salts and amine salts,poly-2-acrylamido-2-methyl-1-propanesulfonic acid copolymers and theiralkali metal salts and amine salts. If desired, two or more of theseresins may be combined for use herein. However, the present invention isnot limited to these examples.

In case where at least one water-soluble resin is partially crosslinkedand the resin is applied onto the image forming layer to form anovercoat layer, crosslinking is carried out at the reactive functionalgroup of the water-soluble resin. The crosslinking may be any one ofcovalent bond crosslinking and ionic bond crosslinking.

Due to the crosslinking, the surface adhesiveness of the overcoat layerlowers and the handlability of the planographic printing plate precursorhaving the overcoat layer is improved. However, if the polymer is toomuch crosslinked, the hydrophilicity of the overcoat layer lowers, andeliminate of the overcoat layer is difficult when the precursor isprocessed in printers. Therefore, in case where a crosslinking agent isused along with the resin to form the overcoat layer, it is desirablethat the crosslinking reaction is controlled to achieve a suitabledegree of partial crosslinking. The preferable degree of partialcrosslinking of the resin is as follows. When the planographic printingplate precursor coated with the overcoat layer comprising the partiallycrosslinked resin is dipped in water at 25° C., the hydrophilic overcoatlayer remains as it is for 30 seconds to 10 minutes without elution, butelution thereof is shown after 10 minutes or more.

The compound to be used for the crosslinking reaction (crosslinkingagent) may be any known polyfunctional compound having the ability ofcrosslinking. Examples thereof include polyepoxy compounds, polyaminecompounds, polyisocyanate compounds, polyalkoxysilyl compounds, titanatecompounds, aldehyde compounds, polyvalent metal salt compounds, andhydrazines.

One or more different types of crosslinking agents may be used hereinsingly or in combination of two or more. Especially preferable examplesfor use herein include water-soluble crosslinking agents. However,water-insoluble crosslinking agents can also be used, by dispersing themin water with a dispersant.

Especially preferable combinations of the water-soluble resin and thecrosslinking agent are carboxylic acid-containing water-solubleresin/polyvalent metal compound, carboxylic acid-containingwater-soluble resin/water-soluble epoxy resin, hydroxyl group-containingresin/dialdehyde and the like.

Preferably, the amount of the crosslinking agent to be added to thewater-soluble resin is from 2 to 10% of the resin. Within the range, theovercoat layer has good resistant to water, and the layer is readilyremoved when the plate is processed in printers.

If desired, the overcoat layer may contain a light to heat convertingagent for improving the sensitivity of the printing plate precursor. Asthe light to heat converting agent, preferable agents are water-solubleIR-absorbing dyes. Especially preferable dyes are those represented bythe general formulae shown above in the description of the image forminglayer.

In case where the coating liquid for the overcoat layer is an aqueoussolution, a surfactant, typically a nonionic surfactant, may be addedthereto in order for forming a uniform film of the layer. Examples ofthe nonionic surfactant include sorbitan tristearate, sorbitanmonopalmitate, sorbitan trioleate, stearinomonoglyceride,polyoxyethylene nonylphenyl ether, and polyoxyethylene dodecyl ether.

The amount of the nonionic surfactant that may be comprised in theovercoat layer is preferably from 0.05 to 5%, more preferably from 1 to3% of the total solid content of the layer.

The thickness of the overcoat layer is preferably 0.1 μm to 4.0 μm, andmore preferably 0.1 μm to 1.0 μm when the water-soluble resin for thelayer is not crosslinked. On the other hand, when the water-solubleresin is partially crosslinked, the thickness of the overcoat layer ispreferably 0.1 to 0.5 μm, and more preferably 0.1 to 0.3 μm. Within therange, the overcoat layer is well effective for preventing the imageforming layer from being stained by oleophilic substances and is readilyremoved while processed in printers.

Method of Image Formation of the Present Invention:

The planographic printing plate precursor thus produced of the presentinvention may be exposed and developed in any known method into aplanographic printing plate, and this is used in producing a largenumber of prints.

Image formation of the planographic printing plate precursor is achievedby heat. In case where the precursor contains a light to heat convertingmaterial, the precursor can be heated through scanning exposure to IRlaser light and the like which is applied for image formation.

Concretely, the image formation includes direct imagewise recording withthermal recording head; scanning exposure to IR laser light;high-intensity flash exposure to xenon discharge lamp; and exposure toIR lamp. Preferred is exposure to light of high-power solid IR lasersuch as 700-1200 nm IR semiconductor laser or YAG laser.

An image may be formed on the planographic printing plate precursor ofthe present invention through exposure to laser light having an outputpower of from 0.1 to 300 W. In case where a pulse laser is used for theimage formation, its peak power is preferably 1000 W, more preferably2000 W. The face exposure intensity before modulation on the printingimage is preferably from 0.1 to 10 J/cm², more preferably from 0.3 to 1J/cm². In case where the substrate of the printing plate precursor istransparent, the precursor may be exposed to light applied theretothrough the back surface of the substrate.

After the precursor is imagewise-exposed but it is not furtherprocessed, the planographic printing plate precursor of the presentinvention may be directly set in a printer. The precursor, which is set,is developed by an ordinary printing operation wherein damping water,ink and printing paper are applied thereto, and then successively usedto produce prints.

The planographic printing plate precursor of the present invention canalso be used in a printing system in which the precursor is set on aprinting cylinder of a printer, then exposed to laser light mounted onthe printer, successively developed in the printer and used to produceprints.

Substrate (Support):

The substrate used for the planographic printing plate precursor in thepresent invention is not specifically defined, and may be any one whichis tabular substrate having good dimensional stability that satisfies arequired strength, durability and flexibility. Examples thereof includespaper, paper laminated with plastic (e.g., polyethylene, polypropylene,polystyrene), metal sheets (e.g., aluminium, zinc, copper), plasticfilms (e.g., cellulose diacetate, cellulose triacetate, cellulosepropionate, cellulose butyrate, cellulose acetate butyrate, cellulosenitrate, polyethylene terephthalate, polyethylene, polystyrene,polypropylene, polycarbonate, polyvinylacetal), metal-laminated ordeposited paper and plastic films described above.

Preferable examples thereof include polyester films and aluminiumplates, and more preferable substrates are aluminum plates, since theirdimensional stability is good and they are relatively inexpensive.

Preferably, the aluminium plates for use in the present invention may bepure aluminum plates or aluminium-based alloy plates containing traceamount of hetero elements. Aluminium-laminated or deposited plasticfilms or papers are also preferable. Examples of the hetero elementsthat may be comprised in the aluminium alloy include silicon, iron,manganese, copper, magnesium, chromium, zinc, bismuth, nickel, andtitanium. Content of the hetero elements comprised in the alloy is atmost 10% by weight. In the present invention, pure aluminium ispreferable as the substrate. However, it is difficult to produce 100%pure aluminum in view of the smelting technology. Therefore, aluminumcontaining trace amount of hetero elements is usable for the substrate.The aluminum plate used for the substrate in the present invention isnot specifically defined in point of its composition, and any knownaluminium plate generally used in the art is usable herein. Thethickness of the aluminium plate for use in the present invention isapproximately from 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, andmore preferably 0.2 mm to 0.3 mm.

An aluminum plate used as the substrate may be subjected to a surfacetreatment, such as a surface roughening treatment and an anodicoxidation treatment, depending on necessity. The surface treatment willbe briefly described below.

Before surface roughening of the aluminum plate, a degreasing treatmentis carried out with a surfactant, an organic solvent or an alkalineaqueous solution, in order to remove a rolling oil from the surface ofthe plate. The surface roughening treatment of the surface of thealuminum plate may be carried out by various methods. For example, itmay be carried out by a method of mechanically roughening, a method ofelectrochemically dissolving and roughening the surface, and a method ofchemically and selectively dissolving the surface. As the mechanicalmethod, a known method such as a ball grinding method, a brush grindingmethod, a blast grinding method and a buff grinding method can be used.Examples of the electrochemical surface roughening method include amethod wherein a plate is treated in a hydrochloric or nitric acidelectrolytic solution with an alternating current or a direct current. Amethod combining both methods disclosed in JP-A No. 54-63902 may also beutilized.

The aluminum plate having a surface thus roughened is subjected,depending on necessity, to an alkaline etching treatment and aneutralizing treatment, and then it is subjected to an anodic oxidationtreatment optionally in order to improve the water holding capacity andthe wear resistance of the surface. As an electrolyte used for theanodic oxidation treatment of the aluminum plate, various kinds ofelectrolytes that form a porous oxide film can be used. In general,sulfuric acid, phosphoric acid, oxalic acid, chromic acid and a mixedacid thereof are used as the electrolyte. The concentration of theelectrolyte is suitably determined depending on the kind of theelectrolyte.

The treating conditions of the anodic oxidation cannot be necessarilydetermined because they are variously changed by the electrolyte used.However, in general, it is suitable when the concentration of theelectrolyte is from 1 to 80% by weight, the liquid temperature is from 5to 70° C., the electric current density is from 5 to 60 A/dm², thevoltage is from 1 to 100 V, and the electrolysis time is from 10 secondsto 5 minutes. When the amount of the anodic oxidized film is less than1.0 g/m², the printing durability becomes insufficient, and thenon-image part of the planographic printing plate is liable to bedamaged, whereby the so-called “flaw contamination” is tend to occur byattaching an ink to the flaw upon printing.

In the present invention, in addition to aluminum, paper laminated withplastics (for example, polyethylene, polypropylene and polystyrene), ametal plate (for example, aluminum, zinc and copper), a plastic film(for example, cellulose diacetate, cellulose triacetate, cellulosepropionate, cellulose butyrate, cellulose acetate butyrate, cellulosenitrate, polyethylene terephthalate, polyethylene, polystyrene,polypropylene, polycarbonate and polyvinyl acetal), and paper or aplastic film having the foregoing metals laminated thereon orvapor-deposited thereon are also used as a substrate.

The aluminum plate used for the substrate may be treated optionally byordinary methods such as surface roughening treatment or anodicoxidation.

When plastic film such as polyester film is used as the substrate, it isalso preferable that the surface of the film to be coated with ahydrophilic layer in the present invention is roughened in an ordinarymanner, in order for facilitating the formation of the hydrophilic layerthereon and for improving the adhesiveness between the hydrophilic layerand the image forming layer to provided thereon.

The surface properties of the surface-roughened substrate preferablysatisfy the following requirements.

The preferable condition of the surface-roughened substrate is indicatedby two-dimensional roughness parameters which are as follows.Preferably, the substrate satisfies at least one, more preferably all ofthe requirements of two-dimensional roughness parameters: The centerline mean roughness (Ra) is from 0.1 to 1 μm; the maximum height (Ry) isfrom 1 to 10 μm; the ten-points mean roughness (Rz) is from 1 to 10 μm;the concave-to-convex mean distance (Sm) is from 5 to 80 μm; theconvex-to-convex mean distance measured in the predetermine range(S) isfrom 5 to 80 μm; the maximum height (2) (Rt) is from 1 to 10 μm; thecenter line convex height (Rp) is from 1 to 10 μm; and the center lineconcave depth (Rv) is from 1 to 10 μm.

The two-dimensional roughness parameters are defined as follows:

Centerline Mean Roughness (Ra):

A length L is measured in the direction of the centerline from aroughness curve. Absolute values of the variation of length from theroughness curve to the centerline are arithmetically averaged. Thearithmetic average indicates the centerline mean roughness (Ra).

Maximum Height (Ry):

A predetermined length is determined in the direction of the average ofthe roughness curve, and within the length, the distance between convex(crest) line and concave (trough) line is measured in the direction ofthe longitudinal magnification of the roughness curve. This distanceindicates the maximum height (Ry).

Ten-Point Mean Roughness (Rz):

A predetermined length is determined in the direction of the average ofthe roughness curve. Within the length, each height of convex portionwhich is highest to convex portion which is fifth, and each depth ofconcave portion which is lowest to convex portion which is fifth aremeasured in the direction of the longitudinal magnification of the meanline. The average value (Yp) of the absolute values of the height of thefirst to fifth highest convex, and the average (Yv) of the absolutevalues of the depth of the first to fifth deepest concave are summed up.The sum of the two average values indicates the ten-point mean roughness(Rz) having a unit of micrometer (μm).

Concave-to-Convex Mean Distance (Sm):

A predetermined length is determined in the direction of the average ofthe roughness curve. Within the length, each of lengths of the mean linebetween one convex portion and the concave portion neighboring to theconvex portion are measured and summed up. Obtained value isarithmetically averaged. The arithmetic average indicates theconvex-to-concave mean distance (Sm) having a unit of micrometer (μm).

Convex-to-Convex Mean Distance Measured in the Predetermine Range (S):

A predetermined length is determined in the direction of the average ofthe roughness curve. Within the length, each of lengths of the mean linebetween the neighboring convex portions (crests) is measured. All thelengths thus measured are arithmetically averaged. The arithmeticaverage value indicates the convex-to-convex mean distance (S) having aunit of micrometer (μm).

Maximum Height (2) (Rt):

A predetermined length is determined in the direction of the average ofthe roughness curve. Within the length, the centerline in the determinedlength is sandwiched between two straight lines both parallel to thecenterline, and the distance between the two straight lines is measured.This indicates the maximum height (2) (Rt).

Center Line Convex Height (Rp):

A length L is measured in the direction of the centerline from aroughness curve. Within the length, a straight line tangent to thehighest convex peak and parallel to the centerline is drawn, and thedistance between the straight line and the centerline is measured. Thisindicates the center line convex height (Rp).

Center Line Concave Depth (Rv):

A length L is measured in the direction of the centerline from aroughness curve. Within the length, a straight line tangent to thedeepest concave bottom and parallel to the centerline is drawn, and thedistance between the straight line and the centerline is measured. Thisvalue indicates the center line valley depth (Rv).

Method of Surface Roughening Treatment of Substrate

In order to treat the surface of the substrate by the surface rougheningtreatment, various known methods can be employed. Examples thereofinclude a method in which the surface of the substrate is mechanicallyground by sand blast or brush to form concave parts for surfaceroughening, a method in which unevenness is formed by mechanicalembossing, and a method in which convexes are formed on the surface bygravure printing. In addition to these surface roughening methodswherein the surface of the substrate itself is physically processed, itis also possible to use a method wherein a layer containing solid fineparticles (matting agent) is formed on a surface of a substrate bycoating, printing or the like, so as to effect surface roughening. Thesolid fine particles may be contained in a plastic material in the stepof forming the plastic film (internal addition), and then unevenness isformed on the surface when the plastic material is shaped into a filmform. Furthermore, the surface roughening can be carried out by usingknown surface treating method, such as a solvent treatment, a coronadischarge treatment, a plasma treatment, an electron beam irradiationtreatment and an X-ray irradiation treatment. The foregoing methods maybe carried out singly or may be used in combination of two or more.

Among these treatments, the method of forming a roughened surface bysand blast or printing a resin, and a method of forming unevenness byadding solid fine particles into the film material are particularlypreferable, and preferably carried out.

Surface Roughening Method by Solid Fine Particles

As the solid fine particles used for forming unevenness on the film,various kinds of substances such as metal fine particles, metal oxidefine particles, and organic or inorganic polymer material fine particlesor low molecular weight material fine particles can be utilized.Specific examples of the fine particles include copper powder, tinpowder, iron powder, zinc oxide powder, silicon oxide powder, titaniumoxide powder, aluminum oxide powder, molybdenum disulfide powder,calcium carbonate powder, clay, mica, corn starch, boron nitride,silicone resin particles, polystyrene resin particles, fluorine resinparticles, acrylic resin particles, polyester resin particles,acrylonitrile copolymer resin particles, zinc stearate and calciumbehenate.

The average particle diameter of the fine particles is preferably 0.05μm or more, and more preferably 0.1 μm or more. In the case where thefine particles are attached to the surface of the sheet as thesubstrate, or a layer containing the fine particles is provided on thesurface of the sheet, the average particle diameter of the fineparticles substantially corresponds to the size of the unevenness of theroughened surface. In the case where the fine particles are internallyadded to the sheet, the average particle diameter of the fine particlesand the thickness of the sheet determined the size of the unevenness ofthe roughened surface. Therefore, in order to obtain optimum size ofunevenness in the later case (internal addition), it is necessary thatthe optimum particle diameter be experimentally determined in accordancewith combinations of the sheets and the fine particles.

Specific examples of the method of forming unevenness by fixing thesolid fine particles on the surface of the substrate include a method inwhich the solid fine particles are added as a material before formingthe film, and then the film is formed, a method in which a liquidcontaining the solid fine particles dispersed in a binder is coated anddried, a method in which after forming the film, the fine particles arepressed into the film with mechanical pressure, and a method in whichthe solid fine particles are electrically attached after forming thefilm.

Specific examples of the method, in which the solid fine particles areadded before forming the film and then the film is formed, include thefollowing methods. A master batch of polyethylene terephthalate (PET)containing a pigment mixed as the solid fine particles is subjected tomelt extrusion, and then a film thereof is provided on a cooling drum.Then, the film is stretched in a longitudinal direction and stretchedsequentially in a transversal direction, and finally it is subjected toa heat treatment, whereby a PET film having unevenness is obtained. Asthe pigment, one or two or more kinds of inorganic pigments, such astitanium oxide, alumina and silica, can be used. The centerline averagesurface roughness of the film can be adjusted by the particle diameterand the mixing amount of the pigment used. For example, the center lineaverage surface roughness can be adjusted by mixing a pigment having aparticle diameter of from 1 to 10 μm in an amount of from 0.5 to 5% byweight, and when the particle diameter of the pigment is larger, or themixing amount thereof is larger, the center line average surfaceroughness is increased. In order to obtain objective uneven surface, itis necessary that the particle diameter of the pigment is determined,and the mixing amount thereof is adjusted.

Sand Blast Method

The sand blast is a method wherein abrasives having a small particlesize are blown at a high speed onto a surface of a polymer film to makeunevenness on the surface of the film. Concretely, in the sand blasttreatment, abrasives are blown onto the film surface by compressed airto carry out the surface treatment. The unevenness formed thereby isadjusted by the conditions of the sand blast treatment. Known methodsmay be used as the sand blast treatment. For example, carborundum(silicon carbide powder) or metal particles can be powerfully blown ontothe film surface along with compressed air, followed by water washingand drying, so as to achieve the object.

The center line average surface roughness of the film which is processedby the sand blast treatment can be controlled by the particle diameterand the treating amount (i.e., treating frequency per unit area) of theparticles to be blown. When the particle diameter of the particles islarger, or the treating amount is larger, the center line averagesurface roughness of the film surface is increased.

When the abrasive (grinding material) is sprayed from a sand blastblowing nozzle onto the film, the blowing amount (blast amount) of theabrasive and the angle and the distance between the sand blast blowingnozzle and the film (i.e., the blast angle and the blast distance) asthe treating conditions need to be adjusted. The abrasive in a hopper isblown from the sand blast blowing nozzle with compressed air anddischarged from an air chamber onto the film surface, and thus the sandblast treatment is carried out under appropriate treating conditions.The method is specifically described, for example, as known methods inJP-A No. 8-34866, No. 11-90827 and No. 11-254590.

It is necessary that the conditions of processing for the sand blasttreatment are that the grinding material and ground matters do notremain on the film surface after the treatment, and the strength of thefilm is not lowered. Such treating conditions can be properlydetermined.

Concretely, silica sand or the like is used as the grinding material,and silica sand having a particle diameter of from 0.05 to 10 mm ispreferably used, and silica sand having a diameter of from 0.1 to 11 mmis more preferable. The blast distance is preferably from 100 to 300 mm,and the blast angle is preferably from 45 to 90°, and more preferablyfrom 45 to 60°. The blast amount is preferably from 1 to 10 kg/min.These conditions are set in order that the abrasive and ground mattersdo not remain on the plastic film surface and the like after the sandblast treatment, and the grinding depth is controlled. The grindingdepth is preferably suppressed in a range of from 0.01 to 0.1 μm. Inthis range, phenomenon such that the strength of the film is lowered bygrinding to fail to maintain the practical strength can be prevented.

Substrate for the Third Aspect:

The surface hydrophilic member (material) of the third aspect of thepresent invention can be obtained by coating the hydrophilic coatingcomposition on a suitable base material, followed by heating and drying,to form a surface hydrophilic layer. The heating temperature and theheating time for forming the hydrophilic layer are not particularlylimited as far as they are suitable temperature and time that can removethe solvent in the sol liquid to form a firm film. From the standpointof production suitability, the heating temperature is preferably 200° C.or less, and the heating time is preferably 1 hour or less.

As the base material that can be used in the third aspect of the presentinvention, for example, a transparent base material can be used when ananti-fogging effect is expected, and glass and plastics can bepreferably used as the material. Examples of use, purpose and material,to which the member having an anti-fogging effect can be applied by thepresent invention, include mirrors such as a rear view mirror for avehicle, a mirror for a bath room, a mirror for a lavatory, a mirror fordental use and a street mirror; lenses such as a lens for eyeglasses, anoptical lens, a lens for a camera, a lens for an endoscope, a lens forlighting, a lens for a semiconductor and a lens for a copy machine;prisms; window glass for a building and a watchtower; window glass for aconveyance such as an automobile, a railway vehicle, an aircraft, awatercraft, a submarine, a snow vehicle, a gondola of an aerial railway,a gondola in an amusement park, and a space craft; a wind shield for aconveyance such as an automobile, a railway vehicle, an aircraft, awatercraft, a submarine, a snow vehicle, a snowmobile, a motorcycle, agondola of an aerial railway, a gondola in an amusement park, and aspace craft; glass for a protecting goggle, a sports goggle, a shieldfor a protecting mask, a shield for a sports mask, a shield for ahelmet, and a display case for frozen foods; cover glass for a measuringinstrument; and a film for attached on the surface of the foregoingarticles.

In the case where the surface cleaning effect is expected in the surfacehydrophilic material of the present invention, metals, ceramics, glass,plastics, wood, stone, cement, concrete, fibers, cloth, combinationsthereof and laminated bodies thereof can be preferably used as the basematerial (substrate) of the materials. Examples of purpose, use andmaterial to which a surface cleaning effect can be applied by thepresent invention include a building material, an exterior of abuilding, an interior of a building, a window frame, a window glass, astructural member, an exterior and painting of a conveyance, an exteriorof mechanical equipment and articles, an antidust cover and painting, atraffic sign, various kinds of display devices, an advertising pillar, asound barrier wall for a road, a sound barrier wall for a railway, abridge, an exterior and painting of a guardrail, an interior andpainting of a tunnel, an insulator, a cover for a solar cell, acollector cover for a solar water heater, a plastic hothouse, a coverfor a panel lamp for a vehicle, a housing fixture, a lavatory pan, abath tub, a washbowl, a light fixture, a cover for illumination, akitchen equipment, a food vessel, a dish washer, a dish dryer, a sink, acooking range, a kitchen hood, an exhaust fan, and a film for attachedon the surface of the foregoing articles.

In the case where the antistatic effect is expected in the surfacehydrophilic material of the third aspect of the present invention,examples which are preferably used as the substrate include metals,ceramics, glass, plastics, wood, stone, cement, concrete, fibers, cloth,combinations thereof and laminated bodies thereof. Examples of theapplicable purpose, use and material include a housing, a part, anexterior and painting of a cathode ray tube, a magnetic recordingmedium, an optical recording medium, a magnetoopitical recording medium,an audio tape, a video tape, an analog phonograph record and a householdelectric equipment, a housing, a part, an exterior and painting of anoffice automation equipment, a building material, an exterior of abuilding, an interior of a building, a window frame, a window glass, astructural member, an exterior and painting of a conveyance, an exteriorof mechanical equipment and articles, an antidust cover and painting,and a film for attaching on the surface of the foregoing articles.

As the substrate used for the third aspect of the present invention, asubstrate having a surface formed with a polymer resin is preferablyused, even if inorganic base materials such as glass and ceramics isused. Examples of the resin base material includes all of a resinitself, a substrate wherein the surface thereof is coated with a resinand a composite material having a resin layer as a surface layer.

Examples of the resin itself include a film substrate such as ananti-scattering film, a designed film and a corrosion resistant film;and a resin substrate used for an advertising display and a soundbarrier wall of an express highway. Examples of the substrate having aresin coating include a body of an automobile, a coated plate such as acoated building material, a laminated plate having a resin film adheredon the surface thereof, a substrate treated with a primer, and asubstrate subjected to a hardcoat treatment. Examples of the compositematerial having a resin layer as a surface include a resin sealingmaterial having an adhesive layer on the back surface thereof and areflective mirror.

EXAMPLES

Examples of the present invention are described below. However, thescope of the present invention is not limited to these examples.

Examples 1 to 3 and Comparative Example 1 Production Example 1Production of Specific Hydrophilic Polymer

50 g of acrylamide, 3.4 g of mercaptopropyl trimethoxysilane, and 220 gof dimethylacetamide were put into a 500-ml three-neck flask, and then0.5 g of 2,2-azobis(2,4-dimethylvaleronitrile) was added thereto at 65°C. in a nitrogen atmosphere. After the temperature was kept for 6 hourswith stirring, this solution was cooled to room temperature. Thesolution was put into 2 liters of ethyl acetate, and the precipitatedsolid was taken out through filtration, and washed with water to obtaina hydrophilic polymer (1). Dry weight of the polymer was 52.4 g.Weight-average molecular weight of the polymer was measured by GPC(polystyrene standard), and the weight-average molecular weight thereofwas 3000. Measurement of the polymer by ¹³C-NMR (DMSO-d₆) confirmed thatthe polymer has a structure of Compound 3-1 mentioned above, terminatedwith a trimethoxysilyl group (50.0 ppm). (General formula of theCompound 1 is shown in the examples of the specific hydrophilic polymer,wherein Compounds 1 to 12 are included.)

Example 1 Positive Planographic Printing Plate Precursor Preparation ofSubstrate

An aluminum plate (material: #1050) having a thickness of 0.30 mm wasdegreased by washing it with trichloroethylene. Using a nylon brush andan aqueous suspension of a 400-mesh pumiston, surface of the plate wassand-grained, and then washed well with water. This plate was etched bydipping the plate in a 25% (by weight) aqueous solution of sodiumhydroxide at 45° C. for 9 seconds, then washed with water, and furtherwashed by dipping it in 2% (by weight) nitric acid for 20 seconds.Through the process, etched amount of the sand-grained surface of theplate was about 3 g/m².

Next, direct current anodic oxide film having a thickness of 2.4 g/m² isformed on the plate by using 7% (by weight) sulfuric acid as anelectrolytic solution and a current density of 15 A/dm² The plate waswashed with water and dried to obtain as a substrate used in theExample.

Formation of Hydrophilic Layer:

The components mentioned below were uniformly mixed, and stirred at 20°C. for 2 hours for hydrolysis. As the result, a sol-like hydrophiliccoating liquid composition 1 is obtained. Hydrophilic Coating LiquidComposition 1:

Hydrophilic polymer (1) 0.21 g Tetramethoxysilane (crosslinkingcomponent) 0.62 g Ethanol 4.70 g Water 4.70 g Aqueous solution of nitricacid (1 N) 0.10 g

This composition solution was applied onto the aluminium substrate tohave a dry weight of 2 g/m², and dried at 100° C. for 10 minutes to formthereon a hydrophilic layer of an organic/inorganic composite.

The contact angle (to a water drop in air) of the surface of thehydrophilic layer thus formed was measured with CA-Z (manufactured byKyowa Kaimen Kagaku Co., Ltd.), and was 7.9°. This result shows goodhydrophilicity of the hydrophilic layer surface.

Formation of Image Forming Layer:

Using a rod bar #15, a coating liquid 1 for image forming layermentioned below was applied onto the hydrophilic layer to have a dryweight of 1.0 g/m², and dried at 80° C. for 5 minutes to form a positiveimage forming layer thereon. This was a planographic printing plateprecursor of Example 1.

Coating Liquid 1 for Positive Image Forming Layer, Containing SulfonatePolymer:

Sulfonate polymer [Compound (1p-4)] 0.40 g IR absorbent dye (IRG22(trade name), manufactured by Nippon 0.05 g Kayaku Co., Ltd.) Methylethyl ketone 4.00 gEvaluation of Planographic Printing Plate Precursor of Example 1:

Using Pearl Setter (manufactured by Presstek, Inc, IR laser which emits908 nm light, power 1.2 W, main scanning rate is 2 m/sec), the positiveplanographic printing plate precursor was exposed imagewise. Withoutdevelopment, the exposed precursor was directly set in a printer (SOR-Mmanufactured by Heidelberg Co.), and printing was started. The dampeningwater used were IF201 (2.5%) and IF202 (0.75%) (both manufactured byFuji Photo Film Co., Ltd.); and the ink used was GEOS-G Black(manufactured by Dainippon Ink & Chemicals, Inc.). In the initial stageof the printing, the non-image area of the image forming layer of theprinting plate was removed, and high-quality prints were obtained. Theprinting was continued, and 6,000 or more good prints having no stain inthe non-image area were obtained. This result shows that thehydrophilicity of the printing plate obtained is good and the printingdurability thereof is also good.

Comparative Example 1

Positive Photosensitive Planographic Printing Plate Precursor

A positive planographic printing plate precursor was fabricated in thesame manner as in Example 1, except that polyacrylamide (aweight-average molecular weight is 1,500) was used instead of thehydrophilic polymer terminated with a silane coupling group (1)comprised in the hydrophilic coating liquid composition 1. Thisprecursor was exposed, developed and used in printing also in the samemanner as in Example 1.

At the start of printing, the printing plate provided good prints havingno stain in the non-image area. However, the prints were graduallystained. After 500 prints were printed, the image area and the non-imagearea comprised in the prints could not be differentiated. This meansthat the hydrophilicity of the non-image area of the printing plategradually lowered while the printing was continued.

Example 2

Negative Thermo-Sensitive Planographic Printing Plate Precursor

The components mentioned below were uniformly mixed, and stirred at 60°C. for 2 hours for hydrolysis. As the result, a sol-like hydrophiliccoating liquid composition 2 was obtained.

Hydrophilic Coating Liquid Composition 2:

Hydrophilic polymer (Compound 3-9 shown above) 0.21 g Tetramethoxysilane0.62 g Ethanol 4.70 g Water 4.70 g Aqueous solution of nitric acid (1 N)0.10 g

This composition solution was applied onto the same aluminium substrateas in Example 1 to have a dry weight of 2 g/m², and dried at 100° C. for10 minutes to form thereon a hydrophilic layer comprising anorganic/inorganic composite. The hydrophilic layer-coated substrate forplanographic printing plate precursor was used in the Example.

The contact angle (to a water drop in air) of the surface of thehydrophilic layer thus formed was measured with CA-Z (manufactured byKyowa Kaimen Kagaku Co., Ltd.), and was 8.3°. This result shows goodhydrophilicity of the hydrophilic layer surface.

Formation of Image Forming Layer:

Using a rod bar #15, a coating liquid 2 for image forming layermentioned below was applied onto the hydrophilic layer to have a dryweight of 1.0 g/m², and dried at 80° C. for 5 minutes to form a negativeimage forming layer thereon. This was a planographic printing plateprecursor of Example 2.

Coating Liquid 2 for Image Forming Layer which is ContainingSulfonylacetate Polymer:

Sulfonylacetate polymer [Compound (P-9)] 0.40 g IR absorbent dye I(having a structural formula mentioned 0.05 g below) Water 4.00 g IRAbsorbent Dye I:

Evaluation of Planographic Printing Plate Precursor of Example 2:

Using Trend Setter 3244VFS manufactured by Creo Corp., which wasequipped with a water-cooling type 40 W IR semiconductor laser, thenegative planographic printing plate precursor was exposed imagewise toform an image area, which was exposed portion of the surface of theprecursor. The number of revolution of outer drum was 100 rpm; theenergy on the precursor surface was 300 mJ/cm²; and the resolution was2400 dpi. Without development, the thus-exposed precursor was directlyset in a printer (SOR-M manufactured by Heidelberg Co.), and printingwas started. The dampening water were IF201 (2.5%) and IF202 (0.75%)(both manufactured by Fuji Photo Film Co., Ltd.); and the ink used isGEOS-G Black (manufactured by Dainippon Ink & Chemicals, Inc.).

In the initial stage of the printing, high-quality images wereimmediately obtained. The printing was continued, and more than 5,000good prints with no stain in the non-image area were obtained. Thisresult shows that the hydrophilicity of the printing plate, in which anegative image forming layer was formed in the precursor, is good andthe printing durability thereof is also good, like in Example 1.

Example 3

Positive Planographic Printing Plat Precursor 2

The same hydrophilic coating liquid composition 1 as in Example 1 wasapplied onto a substrate of corona-discharged polyethylene terephthalatefilm to form a hydrophilic layer thereon.

Using a rod bar #15, a coating liquid 3 for positive image forming layermentioned below was applied onto the hydrophilic layer to have a dryweight of 1.0 g/m², and dried at 80° C. for 5 minutes to form a positiveimage forming layer thereon. This was a planographic printing plateprecursor of Example 3.

Coating Liquid 3 for Image Forming Layer Containing Sulfonate TypePolymer:

Sulfonate polymer [Compound (1p-2) shown above as an 0.40 g example ofthe sulfonate polymer IR absorbent dye (IRG22 (trade name) manufacturedby Nippon 0.05 g Kayaku Co., Ltd.) Methyl ethyl ketone 4.00 gEvaluation of Planographic Printing Plate Precursor of Example 3:

Using Pearl Setter (manufactured by Presstek, Inc, IR laser which emit908 nm laser light, power is 1.2 W, main scanning rate is 2 m/sec), thepositive planographic printing plate precursor was exposed imagewise.Without development, the thus-exposed precursor was directly set in aprinter (SOR-M), and printing was started. The dampening water used wereIF201 (2.5%) and IF202 (0.75%) (both manufactured by Fuji Photo FilmCo., Ltd.); and the ink used is GEOS-G Black (manufactured by DainipponInk & Chemicals, Inc.). In the initial stage of the printing, thenon-image area of the image forming layer of the printing plate wasremoved, and high-quality prints were obtained. The printing wascontinued, and more than 5,000 good prints with no stain in thenon-image area were obtained. This result shows that the hydrophilicityof the printing, in which a PET film was used for the substrate, is goodand the printing durability thereof is also good, like in Example 1 inwhich an aluminium substrate was used.

As shown in the examples, the planographic printing plates obtained fromthe precursor of examples 1 to 3 can maintain a high degree ofhydrophilicity even in severe printing conditions, and its printingdurability is good. The plate can provide a large number of good printsof high quality with no stain in the non-image area. In particular,since the image forming layer in the precursor contains a polymercompound having a polarity-converting group, the precursor can beprocessed through scanning exposure based on digital signals. Afterimagewise-exposure, the precursor can be processed into a printing platethrough simple development with water, or without development, theprecursor can be directly set in a printer to produce prints, andin-printer developability of the precursor is good.

Examples 2 to 6 and Comparative Examples 2 Production Example 2

Production of Specific Hydrophilic Polymer

In the same manner as in Production Example 1, the same polymer wasproduced.

Example 4

Preparation of Substrate:

In the same manner as in Example 1, the same substrate was prepared.

Formation of Hydrophilic Layer:

The components mentioned below were uniformly mixed, and stirred at roomtemperature for 2 hours for hydrolysis. As the result, a sol-likehydrophilic coating liquid composition 3 was obtained.

Hydrophilic Coating Liquid Composition 3:

Hydrophilic polymer (1) 21 g Tetramethoxysilane (crosslinking component)62 g Ethanol 470 g  Water 470 g  Aqueous solution of nitric acid (1 N)10 g

The composition 3 was mixed with the components mentioned below toprepare a coating liquid 3 for hydrophilic layer which can form image.This liquid was applied onto the aluminium substrate to have a dryweight of 3 g/m², and dried at 100° C. for 10 minutes to form thereon ahydrophilic layer. This plate was a planographic printing plateprecursor of the Example 4.

Coating Liquid 3 for Hydrophilic Layer:

Hydrophilic coating liquid composition 3  66 g Thermo-fuseablepolystyrene particles (particle size, 0.2 μm; 400 g melting point, 120°C.) which was stabilized with 1.5% by weight of surfactant relative tothe polymer (aqueous dispersion of 10% by weight of particles) IRabsorbent dye I (mentioned above)  10 g Water 374 g

The contact angle (to a water drop in air) of the surface of the imageforming hydrophilic layer thus formed on the substrate was measured withCA-Z (manufactured by Kyowa Kaimen Kagaku Co., Ltd.), and the angle was6.3°. This result shows good hydrophilicity of the hydrophilic layersurface. Evaluation of Planographic Printing Plate Precursor of Example4:

Using Trend Setter 3244VFS manufactured by Creo Corp., equipped with awater-cooling type 40 W IR semiconductor laser, the planographicprinting plate precursor was exposed imagewise to form an image area,which was the exposed portion of the surface of the precursor. The outerdrum revolution was 100 rpm; the energy on the precursor surface was 200mJ/cm²; and the resolution was 2400 dpi.

The water drop contact angle of the IR laser light-exposed surface ofthe printing plate precursor was 102°. This means that the exposed areaof the precursor surface became hydrophobic, and a hydrophobic region(ink-receiving region) was formed. Without development, theimagewise-exposed precursor was directly set in a printer and used toproduce prints.

The printer used is SOR-M manufactured by Heidelberg Co. The dampeningwater used were IF201 (2.5%) and IF202 (0.75%) (both manufactured byFuji Photo Film Co., Ltd.); and the ink used is GEOS-G Black(manufactured by Dainippon Ink & Chemicals, Inc.). In the initial stageof the printing, high-quality images were immediately obtained. Theprinting was continued, and more than 5,000 good prints with no stain inthe non-image area were obtained. This result shows that thehydrophilicity in the non-image region of the printing plate obtainedfrom the precursor of this Example 4 is good and the printing durabilitythereof is also good.

Comparative Example 2

A positive planographic printing plate precursor was fabricated in thesame manner as in Example 3, except that polyacrylamide (having aweight-average molecular weight of 1,500) was used instead of thehydrophilic polymer terminated with silane coupling group (1) comprisedin the hydrophilic coating liquid composition 3, and this was exposed,developed and used in printing also in the same manner as in Example 3.

At the start of printing, the printing plate gave good prints with nostain in the non-image area. However, the prints given by the plate weregradually stained and the images therein became blurred. After 500prints, the image area and the non-image area in the prints could not bedifferentiated each other. This result means that the hydrophilicity ofthe non-image area of the printing plate gradually lowered while theprinting was continued.

Example 5

Formation of Hydrophilic Layer:

The components mentioned below were uniformly mixed, and stirred at roomtemperature for 2 hours for hydrolysis. As the result, a sol-like,hydrophilic coating liquid composition 4 was obtained.

Hydrophilic Coating Liquid Composition 4:

Compound 3-9 (Hydrophilic polymer shown above) 21 g Tetramethoxysilane(crosslinking component) 62 g Ethanol 470 g  Water 470 g  Aqueoussolution of nitric acid (1 N) 10 g

The composition 4 was mixed with the components mentioned below in orderfor preparing a coating liquid 2 for hydrophilic layer. This liquid wasapplied onto the same aluminium substrate as in Example 1 to have a dryweight of 3 g/m², and dried at 100° C. for 10 minutes to form thereon ahydrophilic layer. This was a planographic printing plate precursor ofthis Example 5.

Coating Liquid 2 for Hydrophilic Layer:

Hydrophilic coating liquid composition 4 66 g Sulfonylacetate polymer[Compound (p-9) which is capable of 40 g changing polarity thereof fromhydrophilic to hydrophobic] IR absorbent dye I 10 g Water 374 g 

The contact angle (to a water drop in air) of the surface of the imageforming hydrophilic layer thus formed on the substrate was measured withCA-Z (manufactured by Kyowa Kaimen Kagaku Co., Ltd.), and the angle was7.80. This result shows good hydrophilicity of the hydrophilic layersurface.

Evaluation of Planographic Printing Plate Precursor of Example 5:

In the same manner as in Example 4, the planographic printing plateprecursor of the Example 5 was exposed imagewise to form an image regionon the surface of the precursor.

The water drop contact angle of the IR laser light-exposed surface ofthe printing plate precursor was 98°. This means that the exposed areaof the precursor surface became hydrophobic, and a hydrophobic region(ink-receiving region) was formed. Without development, theimagewise-exposed precursor was directly set in a printer and used toproduce prints, in the same manner as in Example 4. In the initial stageof the printing, high-quality images were immediately obtained. Theprinting was continued, and more than 5,000 good prints with no stain inthe non-image area were obtained. This result shows that thehydrophilicity in the non-image region of the printing plate obtainedfrom the precursor of this Example 6 is good and the printing durabilitythereof is also good. From this, it is understood that the planographicprinting plate precursor of the Example 5, wherein a compound capable ofchanging their property from hydrophilic to hydrophobic was used as acompound to form a hydrophilic surface region, can also exhibitexcellent effect of the present invention like the precursor of Example4 in which thermo-fuseable hydrophobic particles were used.

Example 6

The same coating liquid 3 for image forming hydrophilic layer as inExample 4 was applied onto a corona-treated polyethylene terephthalatefilm substrate to have a dry weight of 3 g/m², and dried at 100° C. for10 minutes. This was a planographic printing plate precursor of theExample 6.

The contact angle (to a water drop in air) of the surface of the imageforming hydrophilic layer thus formed on the substrate was measured withCA-Z (manufactured by Kyowa Kaimen Kagaku Co., Ltd.), and the angle was6.50. This result shows good hydrophilicity of the hydrophilic layersurface.

Evaluation of Planographic Printing Plate Precursor of Example 6:

In the same manner as in Example 4, the planographic printing plateprecursor of this Example 6 was exposed imagewise to form an imageregion on the surface of the precursor.

The water drop contact angle of the IR laser light-exposed surface ofthe printing plate precursor was 105°. This result means that theexposed area of the precursor surface formed a hydrophobic region(ink-receiving region). Without development, the imagewise-exposedprecursor was directly set in a printer and used to produce prints, inthe same manner as in Example 4. In the initial stage of the printing,high-quality images were immediately obtained. The printing wascontinued, and more than 5,000 good prints with no stain in thenon-image area were obtained. This result shows that the hydrophilicityin the non-image region of the printing plate from the precursor of thisExample 6 is good and the printing durability of the plate is also good.From this, it is understood that the planographic printing plateprecursor of the Example 6, in which a resin film was sued for thesubstrate, also exhibits excellent effect of the present invention.

As shown in the examples, the planographic printing plates obtained fromthe precursors of Examples 4 to 6 can maintain a high degree ofhydrophilicity even in severe printing conditions, and its printingdurability is good. It can give a large number of good prints of highquality with no stain in the non-image area. In particular, theprecursor can be processed through scanning exposure based on digitalsignals. After imagewise-exposure, it can be processed into a printingplate through simple development with water, or without development, itcan be directly set in a printer to produce prints, and its in-printerdevelopability is good.

Examples 7 to 14 Production Example 3

Production of Hydrophilic Polymer (3-1)

In the same manner as in Production Example 1, the same polymer wasproduced.

Production Example 4

Production of Hydrophilic Polymer (3-5)

50 g of N-vinylacetamide, 2.9 g of mercaptopropyltrimethoxysilane, and220 g of dimethylacetamide were put into a 500-ml three-neck flask, and0.5 g of 2,2-azobis(2,4-dimethylvaleronitrile) was added thereto at 65°C. in a nitrogen atmosphere. After kept at the temperature with stirringfor 6 hours, this solution was cooled to room temperature. The solutionwas put into 2 liters of ethyl acetate, and the precipitated solid wastaken out through filtration, and washed with water to obtain ahydrophilic polymer (5). Dry weight of the polymer was 48.5 g.Weight-average molecular weight was determined by GPC (polystyrenestandard), and a weight-average molecular weight of the polymer was2500; and Measurement of the polymer by ¹³C-NMR (DMSO-d₆) confirmed thatthe polymer has a structure of Compound (5) mentioned above which isterminated with a trimethoxysilyl group (50.0 ppm).

Production Example 5

Production of Microcapsules (1)

7.5 g of a phenol-novolak resin having a weight-average molecular weightof 1500 (meta/para=60/40) and 0.1 g of an anionic surfactant (PioninA-41C manufactured by Takemoto Yushi Co., Ltd.) were dissolved in 21.0 gof ethyl acetate to prepare an oily phase. To the oily phase was added36.0 g of 4% aqueous solution of polyvinyl alcohol (PVA205 manufacturedby Kuraray Co., Ltd.) as an aqueous phase. The phases were emulsified bythe use of a homogenizer at 10000 rpm for 10 minutes. 24.0 g of waterwas added thereto, and the resulting liquid was heated at 50° C. for 3hours to remove the organic solvent. The process gave a dispersion ofmicrocapsules (1) wherein microcapsules were used as a hydrophobicprecursor for image forming layer. The solid content concentration ofthe dispersion was measured and was 15.0%. The mean particle size of themicrocapsules (1) was 0.3 μm.

Production Example 6

Production of Microcapsules (2)

40 g of xylylene diisocyanate, 10 g of trimethylolpropane diacrylate, 10g of a copolymer of allyl methacrylate and butyl methacrylate (molarratio thereof=17/3), 0.1 g of an anionic surfactant (Pionin A-41Cmanufactured by Takemoto Yushi Co., Ltd.), and 2 g of an iodonium salthaving a structure mentioned below were dissolved in 60 g of ethylacetate to prepare an oily phase component. 120 g of an aqueous solutionof 4% polyvinyl alcohol (PVA205 manufactured by Kuraray Co., Ltd.) wasprepared as an aqueous phase. The oily phase component and the aqueousphase component were emulsified by the use of a homogenizer at 10000rpm. Next, 40 g of water was added thereto, and stirred at roomtemperature for 30 minutes and then stirred at 40° C. for 3 hours. Theprocess gave a dispersion of microcapsules (2) that are used as ahydrophobic precursor for image forming layer. The solid contentconcentration of the dispersion was 20% by weight. The mean particlesize of the microcapsules (2) was 0.5 μm.

Production Example 7

Production of Polymer Particles (3)

400 g of methyl ethyl ketone was put into a one-liter four-neck flaskequipped with a stirrer, a reflux equipment, a dry nitrogen-introducingtube with a thermometer, and a dropping funnel, and heated up to 80° C.A solution was prepared by mixing 80 g of vinyltoluene, 238.9 g of ethylmethacrylate, 24.5 g of methacrylic acid, 56.6 g of ethyl acrylate and 3g of azobisisobutyronitrile, and the solution was added dropwise to themethyl ethyl ketone over a period of 2 hours. After this solutionobtained was stirred for 6 hours, 0.5 g of azobisisobutyronitrile wasadded thereto and further stirred for 3 hours. As the result, an acrylicpolymer having a solid content concentration of 49.5%, an acid value of0.70 milliequivalents/g (polymer solid), and a mass molecular weight of40,000 was obtained. The solid content concentration was obtained bysampling and measuring 1 part of the polymer solution, heating it at120° C. for 1 hour, measuring the dried sample, and calculating theweight ratio of the samples measured. The weight-average molecularweight was obtained by GPC, through conversion based on molecular weightof polyethylene as a standard substance. The acid value was determinedby sampling a predetermined amount of the polymer solution and titratingit with an aqueous 0.1 N sodium hydroxide solution.

Next, after solvent had been removed from the resin obtained above (theacrylic polymer), 20 g of the resin was dissolved in 50 g of a solventof 1-methoxy-2-propanol/water (mass ratio: 8/2), and 0.84 g oftriethylamine was added thereto. Next, 50 g of an aqueous solution of 5%polyacrylamide was further added thereto, and it was emulsified by theuse of a homogenizer at 15,000 rpm for 15 minutes. This emulsion wasfurther stirred under reduced pressure at 60° C. for 3 hours to removethe organic solvent. The process gave an aqueous dispersion of polymerparticles (3) that serve as a hydrophobic precursor for image forminglayer.

Production Example 8

Production of Polymer Particles (4)

The same process as in Production Example 5 (for producing polymerparticles (3)) was repeated except that 3.3 g of an aqueous 10% sodiumhydroxide solution was added instead of 0.84 g of triethylamine. Thisgave an aqueous dispersion of polymer particles (4) that serve as ahydrophobic precursor for image forming layer.

Production Example 9

Production of Polymer Particles (5)

533 g of Barnock DN-9180 (trade name, polyisocyanate manufactured byDainippon Ink & Chemicals, Inc.), 33.5 g of2,2-bis(hydroxymethyl)propionic acid, 0.05 g of dibutyl tin dilaurate,and 300 g of ethyl acetate were put into a one-liter four-neck flaskequipped with a stirrer, a reflux equipment, a dry nitrogen-introducingtube and a thermometer, and stirred at 80° C. for 3 hours. 50 g ofethanol was added thereto and further stirred at 80° C. for 1 hour totreat the terminal isocyanate group of the polymer, and the polymer wasprecipitated in water. The acid value of the polymer was 0.57milliequivalent/g (polymer solid). The process gave a polyurethaneprepolymer solution having a dry solid content ration of 50.0% and a NCO(isocyanate group) content ratio of 6.80%. The NCO content ratio wasobtained by sampling a predetermined amount of the polymer solution,adding thereto a predetermined amount of an ethyl acetate solutioncontaining di-n-butylamine wherein the amine content was known, suchthat the amount of di-n-butylamine is lager than those of the isocyanategroup to be measured, reacting them, and back-titrating the excessdi-n-butylamine with an aqueous hydrochloric acid solution wherein theconcentration thereof was known.

After the solvent had been removed from the polyurethane prepolymersolution, 20 g of the resin obtained was dissolved in 50 g of a solventof 1-methoxy-2-propanol/water (mass ratio: 8/2), and 1.04 g oftriethylamine was added thereto. Next, 50 g of a 5% aqueous solution ofpolyacrylic acid was further added thereto, and emulsified by the use ofa homogenizer at 15,000 rpm for 15 minutes. This was further stirredunder reduced pressure at 60° C. for 3 hours to remove the organicsolvent. The process gave an aqueous dispersion of polymer particles (5)that serve as a hydrophobic precursor for image forming layer.

Examples 7 to 11

Preparation of Substrate:

In the same manner as in Example 1, the same substrates were prepared.

Formation of Hydrophilic Layer:

The sol-like hydrophilic coating liquid composition 1 was prepared inthe same manner as in Example 1, and this composition was applied ontothe aluminium substrate to form thereon a hydrophilic layer also in thesame manner as in Example 1.

Formation of Image forming Layer:

Coating liquids for image forming layer mentioned below were prepared.Using a rod bar #15, each of the coating liquids was applied onto thehydrophilic layer to have a dry weight of 0.8 g/m², and dried at 60° C.for 3 minutes to form an image forming layer thereon. The process gaveplanographic printing plate precursors of these Examples 7 to 11. Theparticle dispersion described below was prepared by adding distilledwater to the dispersion obtained in each of Production Examples 3 to 7to have a solid content concentration of 10%.

Coating Liquids for Image Forming Layer:

Particle dispersion (the particle therein is a hydrophobic   10 gprecursor described in Table 1) Hydrophilic resin (described in Table 1) 0.1 g Light to heat converting agent (IR-10 mentioned above)  0.1 gMegafac F-177 (fluorine-containing surfactant manufactured by 0.05 gDainippon Ink & Chemicals, Inc.), 20% aqueous solutionDistilled water (that was added such that solid content concentration ofthe coating liquid was 7%)Evaluation of Planographic Printing Plate Precursors of Examples 7 to11:

Using Trend Setter 3224VFS manufactured by Creo Corp., equipped with awater-cooling type 40 W IR semiconductor laser, each planographicprinting plate precursor fabricated above was exposed imagewise. Thepower was 9 W; the number of revolution of the outer drum was 210 rpm;the energy on the precursor surface was 500 mJ/cm²; and resolution was2400 dpi. Without development, the imagewise-exposed precursor wasdirectly set in a printer, which is SOR-M manufactured by Heidelberg Co.Dampening water was first applied thereto, and then ink was alsoapplied. Further, printing paper was applied thereto, and printing wascarried out to produce prints. In the in-printer development andprinting test, the number of copying paper sheets needed for finishingthe in-printer development and the number of good prints which wasobtained during continuous printing (the number of prints which canendure the printing test) were counted. Further, the prints were checkedfor stains (presence or absence of background stains). The test resultsare given in Table 1 below.

TABLE 1 Test Results No. Hydrophilic Printing Printing Layer Papersneeded durability Utilized Image forming Layer for achieving (no. ofgood Stains in Hydrophilic Hydrophobic Hydrophilic in-printer prints,Non-Image Polymer Precursor Resin development 10,000) Area Example 7Hydrophilic microcapsules (1) PVA205 40 3.0 no polymer (1) Example 8hydrophilic microcapsules (2) PVA205 45 4.5 no polymer (1) Example 9hydrophilic polymer particles polyacrylic 55 3.5 no polymer (3) acid (1)Example 10 hydrophilic polymer particles polyacrylic 60 3.0 no polymer(4) acid (5) Example 11 hydrophilic polymer particles polyacrylic 55 5.5no polymer (5) acid (5)

As shown in Table 1, the planographic printing plate precursors ofExamples 7 to 11 were completely developed between the first print andfortieth to sixtieth prints, and gave a large number of good prints ofhigh quality. This result shows that all precursors of Examples 7 to 11have good in-printer developability. In addition, even in the initialstage of the printing, the printing plates obtained from the precursorsimmediately gave good prints with no stain in the non-image area. Whenthe printing was continued, all the printing plates gave more than30,000 good prints having excellent image quality. This result showsthat all the planographic printing plates obtained from the precursorsmaintain good hydrophilicity in the non-image area, and all plates havegood printing durability.

Examples 12 to 14

The same hydrophilic coating liquid compositions as in Examples 7 and 10were prepared and each of the compositions was applied onto substrate,which is a corona-treated polyethylene terephthalate film, to form ahydrophilic layer thereon.

Further, coating liquids for image forming layer were prepared andapplied onto the hydrophilic layers as in Table 2 below. That is, thesame coating liquids for image forming layer as in Examples 7 and 9 wereprepared and each of them was applied onto the hydrophilic layer whichwas prepared in a same manner as in Example 7; and the same coatingliquid for image forming layer as in Example 10 was prepared and appliedonto the hydrophilic layer which was prepared in a same manner as inExample 10. After dried, an image forming layer was formed. These wereplanographic printing plate precursors of Examples 12 to 14.

TABLE 2 Test Results No. of Printing Image forming Layer Papers neededPrinting Utilized for achieving durability Stains in Hydrophilic LayerHydrophobic Hydrophilic in-printer (no. of good Non-Image HydrophilicPolymer Precursor Resin development prints, × 10,000) Area Example 12hydrophilic polymer microcapsules (1) PVA205 40 3.0 no (3-1) Example 13hydrophilic polymer polymer particles polyacrylic 55 3.5 no (3-1) (3)acid Example 14 hydrophilic polymer polymer particles polyacrylic 60 3.0no (3-5) (4) acidAs shown in Table 2, the planographic printing plate precursors of thepresent invention having a PET substrate also have good in-printerdevelopability and give good prints with no stain in the non-image area,and all the printing plates obtained from them have good printingdurability. That is, the planographic printing plate precursors having aPET substrate was excellent similar to those having an aluminumsubstrate

The planographic printing plates obtained from the precursors ofExamples 12 to 14 comprises hydrophilic layer having high hydrophilicityand good durability. Therefore, stain resistance thereof is good. Evenin severe printing conditions, the printing plate can provide a largenumber of good prints with no stain. In addition, the printing plateprecursor of the present invention can be processed into a printingplate through scanning exposure based on digital signals. After thusimagewise exposed, the precursor can be processed into a printing platethrough simple development with water, or without development, it can bedirectly set in a printer to produce prints, and therefore itsin-printer developability is good.

Examples 15 to 29 Example 15

Formation of Image Forming Layer:

In a same manner as in Example 1, a substrate having a hydrophilic layerwas obtained. A coating liquid for image forming layer having acomposition mentioned below was prepared. The coating liquid was appliedonto the hydrophilic layer to have a dry weight of 1.5 g/m², and driedat 100° C. for 30 minutes to form a positive image forming layerthereon. This was a planographic printing plate precursor of the Example15.

Coating Liquid for Positive Image Forming Layer:

Ester of naphtoquinone-(1,2)-diazide-4-sulfonyl chloride with 0.90 gpyrogallol-acetone resin Victoria Pure Blue BOH 0.05 gCresol-formaldehyde novolak resin  2.0 g (meta:para ratio = 6:4,weight-average molecular weight 8,000) Methyl ethyl ketone 20.00 g Methyl alcohol 7.00 gEvaluation of Planographic Printing Plate Precursor of Example 15:

The obtained planographic printing plate precursor was exposed to PSlight through a Step Guide (manufactured by Fuji Photo Film Co., Ltd.).After exposure, the plate was processed through an automatic developingmachine filled with a developer of DP-4 (manufactured by Fuji Photo FilmCo., Ltd.). The precursor processed was set in a printer (SOR-Mmanufactured by Heidelberg Co.), and printing was carried out, and 5,000good prints having no stain in the non-image area were obtained. Thisresult means that the hydrophilicity of the printing plate obtained isgood and the printing durability thereof is also good.

Comparative Example 3

A planographic printing plate precursor was prepared in the same manneras in Comparative Example 1, and same result was obtained.

Example 16

Negative Planographic Printing Plate Precursor:

Formation of Hydrophilic Surface:

A substrate having a hydrophilic layer was prepared in the same manneras in Example 2.

Formation of Image Forming Layer:

A coating liquid for image forming layer having a composition mentionedbelow was prepared. The coating liquid was applied onto the substratehaving hydrophilic layer to have a dry weight of 1.7 g/m², and dried at100° C. for 10 minutes to form a negative image forming layer thereon.This was a planographic printing plate precursor of the Example 16.

Coating Liquid 1 for Negative Image Forming Layer:

Copolymer of P-hydroxyphenyl methacrylamide/2-hydroxyethyl 5.0 gmethacrylate/acrylonitrile/methylmethacrylate/methacrylic acid (Weightratio = 10/20/25/35/10, weight-average molecular weight 60,000) Diazocompound represented by the following formula (V) 0.5 g (Weight-averagemolecular weight 16,500) Victoria Pure Blue BOH 0.1 g Cellulose ethylether 0.2 g Tricresyl phosphate 0.5 g Methyl cellosolve 95 ml Water 5 mlgeneral formula (V)

Evaluation of Planographic Printing Plate Precursor of Example 16:

The resulting planographic printing plate was exposed by Jet Printer2000 (manufactured by Oak Seisakusho Co., Ltd.) through a Step Guide(manufactured by Fuji Photo Film Co., Ltd.) for 50 seconds. Afterexposure, the plate was developed with a following developer. Thedeveloped precursor was set in a printer (SOR-M manufactured byHeidelberg Co.), and printing was carried out, and 6,000 good printshaving no stain in the non-image area were obtained. This result showsthat the hydrophilicity of non-image area is maintained well and theprinting durability thereof is also good.

Developer:

Benzyl alcohol 30 ml Sodium carbonate 5 g Sodium sulphite 5 g Sodiumdodecylbenzene sulfonate 10 g Water 1 L

Example 17

Positive Planographic Printing Plate Precursor:

Preparation of Substrate:

The components mentioned below were uniformly mixed, and stirred at 80°C. for 2 hours for hydrolysis. As the result, a sol-like hydrophiliccoating liquid composition was obtained.

Hydrophilic Coating Liquid Composition:

Hydrophilic polymer (Compound 1-5 shown 0.21 g above) Tetramethoxysilane0.62 g Ethanol 4.70 g Water 4.70 g Aqueous solution of nitric acid (1 N)0.10 g

This composition solution was applied onto a substrate (a corona treatedpolyethlene terephthalate film) to have a dry weight of 2 g/m², anddried at 100° C. for 10 minutes to form thereon a hydrophilic layer. Thehydrophilic layer-coated substrate for planographic printing plateprecursor was used in the Example 17. The contact angle (to a water dropin air) of the surface of the hydrophilic layer thus formed was measuredwith CA-Z (manufactured by Kyowa Kaimen Kagaku Co., Ltd.), and was 8.9°.This result shows good hydrophilicity of the hydrophilic layer surface.

Formation of Image Forming Layer:

A coating liquid for image forming layer having a composition mentionedbelow was applied onto the substrate (corona treated polyethyleneterephthalate film having the hydrophilic layer) to have a dry weight of1.0 g/m², and dried at 100° C. for 10 minutes to form thereon ahydrophilic layer. Thus, planographic printing plate precursor wasobtained.

Coating Liquid for Positive Image Forming Layer:

Ester of naphtoquinone-(1,2)-diazide-4-sulfonyl chloride with 0.9 gpyrogallol-acetone resin Victoria Pure Blue BOH 0.05 g Cresol-formaldehyde novolak resin 2.0 g (meta:para ratio = 6:4,weight-average molecular weight 1800) Methyl ethyl ketone 20.0 g  Methylalcohol 7.0 gEvaluation of Planographic Printing Plate Precursor of Example 17:

The resulting planographic printing plate precursor was exposed to PSlight through a Step Guide (manufactured by Fuji Photo Film Co., Ltd.).After exposure, the plate was processed through an automatic developingmachine filled with a developer of DP-4 (1:8, manufactured by Fuji PhotoFilm Co., Ltd.). The precursor was set in a printer (SOR-M manufacturedby Heidelberg Co.), and printing was carried out, and 5,000 good printshaving no stain in the non-image area were obtained. This result showsthat the hydrophilicity of the non-image area is good and the printingdurability thereof is also good.

Examples 18 to 29

Positive photo-sensitive Planographic Printing Plate Precursor:

Planographic printing plate precursors were formed in a same manner asin Example 15 except that composition of the hydrophilic coating liquidand its coating amount was changed in accordance with following Table 3.

The contact angles (to a water drop in air) of the surface of thehydrophilic layers were measured with CA-Z (manufactured by Kyowa KaimenKagaku Co., Ltd.). These results were also shown in Table 3. Further, ina same manner as in Example 15, positive planographic printing plateprecursors for Examples 18 to 29 were formed.

Evaluation of Planographic Printing Plate Precursors of Examples 18 to29:

Planographic printing plate precursors of Examples 18 to 29 were exposedto, developed and used for printing in as same manner as in Example 15.

All planographic printing plate precursors of Examples 15 to 29 providedprints having high-quality images. Further, each of printing wascontinued. Further, each of printing stain resistance was evaluated when9,000th print and 15,000th print were obtained. Results thereof wereshown in Table 3. As the evaluation of the printing stain resistance,referred to are following results in Table 3.

TABLE 3 Hydrophilic coating liquid composition Surface Weight ratiohydrophilicity Printing stain of hydrophilic Coating Contact resistanceUtilized hydrophilic polymer to amount angle 9,000th 15,000^(th) polymertetramethoxysilane (g/m²) (°) print print Example 18 hydrophilic polymer(1-1) 25/75 0.05 7.3 ∘ ∘ Example 19 hydrophilic polymer (1-1) 25/75 0.037.7 ∘ ∘ Example 20 hydrophilic polymer (1-1) 50/50 0.03 6.5 ∘ ∘ Example21 hydrophilic polymer (1-1) 10/90 0.05 13.2 ∘ Δ Example 22 hydrophilicpolymer (2-1) 25/75 0.10 9.0 ∘ ∘ Example 23 hydrophilic polymer (2-1)10/90 0.05 18.0 Δ Δ Example 24 hydrophilic polymer (1-13) 25/75 0.50 7.9∘ ∘ Example 25 hydrophilic polymer (1-15) 10/90 0.10 12.2 ∘ Δ Example 26hydrophilic polymer (1-16) 25/75 0.05 8.0 ∘ ∘ Example 27 hydrophilicpolymer (1-17) 50/50 0.05 6.5 ∘ ∘ Example 28 hydrophilic polymer (1-22)10/90 0.03 14.1 ∘ Δ Example 29 hydrophilic polymer (1-23) 25/75 0.05 8.0∘ ∘As shown from the Examples 15 to 29, the substrates having hydrophiliclayer used for planographic printing plat precursor of the presentinvention has high hydrophilicity, and the hydrophilicity can bemaintained even in severe printing conditions. Therefore, when thesubstrate is used for a planographic printing plate, printing durabilityof the plate is excellent, and many high quality image prints can beobtained. As described above, the substrate for planographic printingplat precursor of the present invention has comprises hydrophilic layerhaving high hydrophilicity and good durability. Therefore, stainresistance thereof is good. Even in severe printing conditions, theprinting plate can provide a large number of good prints with no stain.

Example 30

Formation of Hydrophilic Surface Material:

The hydrophilic coating liquid composition was prepared in the samemanner as in Example 1, and was applied onto a glass plate (manufacturedby Endo Kagaku Co.) to have a dry weight of 2 g/m², and dried at 100° C.for 10 minutes to form an hydrophilic layer thereon. The plate wassurface hydrophilic material of the Example 30.

Evaluation of Hydrophilic Surface Material of Example 30:

The surface of the surface hydrophilic material obtained was rubbed withnon-woven fabric (BEMCOT, manufactured by Asahi Chemical Industry Co,Ltd.) one hundred times. The contact angles (to a water drop in air) ofthe surface before and after rubbing were measured with CA-Z(manufactured by Kyowa Kaimen Kagaku Co., Ltd.). The surface afterrubbing was observed. No peeling of the layer and no scratch wereobserved. The contact angle before rubbing was 6.5° and those afterrubbing was 6.9°. These results means that the surface hydrophilicmaterial of the present invention can maintain excellent hydrophilicityeven after rubbing as well as before rubbing, and has goof plate wearresistance.

1. A planographic printing plate precursor comprising a substrate havingdisposed thereon a hydrophilic layer which includes hydrophilic graftchains and a crosslinked structure formed through hydrolyticpolycondensation of an alkoxide of an element selected from Si, Ti, Zrand Al, wherein the hydrophilic layer includes a polymer compoundrepresented by the following general formula (I): general formula (I)

wherein each of R¹, R², R³ and R⁴ independently represents a hydrogenatom or a hydrocarbon group having 1 to 8 carbon atoms; m is an integerof 0 to 2; n is an integer of 1 to 8; L represents a single bond or anorganic linking group; Y represents —NHCOR⁵, —CONH₂, —CON(R⁵)₂,—COR⁵,—OH, —CO₂M or —SO₃M; R⁵ represents an alkyl group having 1 to 8carbon atoms; and M represents one of a hydrogen atom, an alkali metal,an alkaline earth metal and an onium and wherein the planographicprinting plate precursor further comprises an image forming layer on thehydrophilic layer, and the image forming layer contains a polymercompound including a functional group that changes from one ofhydrophilic to hydrophobic and hydrophobic to hydrophilic in thepresence of an acid, by application of heat, or by irradiation withradiation.
 2. The planographic printing plate precursor according toclaim 1, wherein the polymer compound including a functional group thatchanges from hydrophobic to hydrophilic is at least one selected fromthe group consisting of secondary sulfonate polymers, tertiarycarboxylate polymers, and alkoxyalkyl carboxylate polymers; and thepolymer compound including a functional group that changes fromhydrophilic to hydrophobic is at least one selected from the groupconsisting of polymers having an ammonium group and polymers having adecarboxylation polarity-changing group represented by the followinggeneral formula:

wherein X represents —O—, —S—, —Se—, —NR³—, —CO—, —SO—, —SO₂—, —PO—,—SiR³R⁴—, or —CS; each of R¹, R², R³ and R⁴ independently represents amonovalent group; and M represents a cation.
 3. A planographic printingplate precursor comprising a substrate having disposed thereon ahydrophilic layer which includes hydrophilic graft chains and acrosslinked structure formed through hydrolytic polycondensation of analkoxide of an element selected from Si, Ti, Zr and Al, wherein thehydrophilic layer includes a Polymer compound represented by thefollowing general formula (I): general formula (I)

wherein each of R¹, R², R³ and R⁴ independently represents a hydrogenatom or a hydrocarbon group having 1 to 8 carbon atoms; m is an integerof 0 to 2; n is an integer of 1 to 8; L represents a single bond or anorganic linking group; Y represents —NHCOR⁵, —CONH₂, —CON(R⁵)₂, —COR⁵,—OH, —CO₂M or —SO₃M; R⁵ represents an alkyl group having 1 to 8 carbonatoms; and M represents one of a hydrogen atom, an alkali metal, analkaline earth metal and an onium and wherein the hydrophilic layerfurther includes a compound that forms a hydrophobic surface region byapplication of heat or irradiation with radiation.
 4. The planographicprinting plate precursor according to claim 3, wherein the compound thatforms the hydrophobic surface region is at least one of a compound thatchanges from hydrophilic to hydrophobic by application of heat orirradiation with radiation, and thermo-fuseable hydrophobic particles,and when the compound that changes from hydrophilic to hydrophobic isused and formed into a film, a contact angle between a surface of thefilm and a water drop in air is at most 20° before the film is heated,and increases to at least 65° after the film has been heated.
 5. Theplanographic printing plate precursor according to claim 3, wherein thecoating liquid composition includes one of an acid catalyst and a basiccatalyst.
 6. A planographic printing plate precursor comprising asubstrate having disposed thereon a hydrophilic layer which includeshydrophilic graft chains and a crosslinked structure formed throughhydrolytic polycondensation of an alkoxide of an element selected fromSi, Ti, Zr and Al, wherein the hydrophilic layer includes a polymercompound represented by the following general formula (I): generalformula (I)

wherein each of R¹, R², R³ and R⁴ independently represents a hydrogenatom or a hydrocarbon group having 1 to 8 carbon atoms; m is an integerof 0 to 2; n is an integer of 1 to 8; L represents a single bond or anorganic linking group; Y represents —NHCOR⁵, —CONH₂, —CON(R⁵)₂, —COR⁵,—OH, —CO₂M or —SO₃M; R⁵ represents an alkyl group having 1 to 8 carbonatoms; and M represents one of a hydrogen atom, an alkali metal, analkaline earth metal and an onium and wherein the hydrophilic layer isformed by preparing a coating liquid composition including thehydrophilic polymer compound represented by general formula (I), acrosslinking component represented by the following general formula(II), and a compound that forms a hydrophobic surface region byapplication of heat or by irradiation with radiation, applying thecoating liquid composition onto a surface of the substrate, thesubstrate comprising aluminum, and drying the coating liquidcomposition: general formula (II)(R⁶)_(m)—X—(OR⁷)_(4−m) wherein each of R⁶ and R⁷ independentlyrepresents an alkyl group or an aryl group; X represents Si, Al, Ti orZr; and m is an integer of 0 to 2.